Updated return types and to align with method return types and included logic to align with comments and annotations.

Author: JamalBWarren

force-app/main/default/classes/VariablesDataTypesOperators.cls

@@ -32,7 +32,12 @@ public with sharing class VariablesDataTypesOperators {
      * @return The sum of the two numbers, or null if either number is null.
      */
     public static Integer addition(Integer a, Integer b) {  
-        return null; // Replace null with the variable you used to store the result
+        if(a == null || b == null){
+            return null;
+        }
+        
+        Integer sum = a + b;
+        return sum; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -44,7 +49,8 @@ public with sharing class VariablesDataTypesOperators {
      * @return The difference between the two numbers.
      */
     public static Integer subtraction(Integer a, Integer b) {
-        return null; // Replace null with the variable you used to store the result
+        Integer difference = a -b;
+        return difference; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -56,7 +62,8 @@ public with sharing class VariablesDataTypesOperators {
      * @return The product of the two numbers.
      */
     public static Integer multiplication(Integer a, Integer b) {
-        return null; // Replace null with the variable you used to store the result
+        Integer product = a * b;
+        return product; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -69,7 +76,12 @@ public with sharing class VariablesDataTypesOperators {
      * @return The quotient of the division, or 0 if the denominator is zero.
      */
     public static Double division(Double a, Double b) {
-        return null; // Replace null with the variable you used to store the result
+        if(b == 0){
+            return 0;
+        }
+
+        Double quotient = a / b;
+        return quotient; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -83,7 +95,8 @@ public with sharing class VariablesDataTypesOperators {
      * @return True if the number is even, False otherwise.
      */
     public static Boolean isEven(Integer num) {
-        return null; // Replace null with the variable you used to store the result
+        Boolean isEven = Math.mod(num, 2) == 0;
+        return isEven; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -94,7 +107,8 @@ public with sharing class VariablesDataTypesOperators {
      * @return true if the number is positive, false otherwise.
      */
     public static Boolean isPositive(Integer num) {
-        return null; // Replace null with the variable you used to store the result
+        Boolean isPositive = num > 0;
+        return isPositive; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -106,7 +120,8 @@ public with sharing class VariablesDataTypesOperators {
      * @return The concatenated string.
      */
     public static String concatenateStrings(String str1, String str2) {
-        return null; // Replace null with the variable you used to store the result
+        String jointString = str1 + str2;
+        return jointString; // Replace null with the variable you used to store the result
     }
 
 	/**
@@ -121,7 +136,8 @@ public with sharing class VariablesDataTypesOperators {
 	 * @return The complete sentence as a single String.
 	 */
 	public static String createSentence(String noun, String verb, String endingPunctuation) {
-		return null; // Replace null with the variable you used to store the result
+		String completeSentence = 'The ' + noun + ' is ' + verb + endingPunctuation;
+        return completeSentence; // Replace null with the variable you used to store the result
 	}
 
     /**
@@ -134,7 +150,8 @@ public with sharing class VariablesDataTypesOperators {
      * @return True if the date is in the past, False otherwise.
      */
     public static Boolean isDateInPast(Date dt) {
-        return null; // Replace null with the variable you used to store the result
+        Boolean dateInThePast = dt < System.Today();
+        return dateInThePast; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -147,7 +164,8 @@ public with sharing class VariablesDataTypesOperators {
      * @return True if the date is today or in the future, False otherwise.
      */
     public static Boolean isDateTodayOrFuture(Date dt) {
-        return null; // Replace null with the variable you used to store the result
+        Boolean dateIsTodayOrLater = dt >= System.Today();
+        return dateIsTodayOrLater; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -159,10 +177,11 @@ public with sharing class VariablesDataTypesOperators {
      * @param minutes The number of minutes.
      * @return The number of milliseconds equivalent to the given number of minutes.
      */
-    Integer MILLISECONDS_PER_MINUTE = null; // Make this value a constant
+    Static Integer MILLISECONDS_PER_MINUTE = 60000; // Make this value a constant
+    
     public static Integer convertMinutesToMilliseconds(Integer minutes) {
-        Integer milliseconds;
-        return null; // Replace null with the variable you used to store the result
+        Integer millisecond = minutes * MILLISECONDS_PER_MINUTE;
+        return millisecond; // Replace null with the variable you used to store the result
     }    
 
     /**
@@ -176,7 +195,8 @@ public with sharing class VariablesDataTypesOperators {
      * @return The average of the three numbers.
      */
     public static Double averageOfThreeNumbers(Integer a, Integer b, Integer c) {
-        return null; // Replace null with the variable you used to store the result
+        Double mean = (a + b + c) / 3;
+        return mean; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -191,10 +211,10 @@ public with sharing class VariablesDataTypesOperators {
      */
     public static Integer adjustOrderOfOperations1(Integer a, Integer b, Integer c) {
         // Add parentheses around the addition operation so that it is performed before multiplication
-        Integer result = a + b * c;
+        Integer result = (a + b) * c;
 
         // Return the result
-        return null; // Replace null with the variable you used to store the result
+        return result; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -206,8 +226,8 @@ public with sharing class VariablesDataTypesOperators {
         // Add parentheses in the below expression to change the result.
         // The result of the expression as it is right now is 43. 
         // You should add parentheses so that the result of the expression becomes 8.
-        Integer answer = 48 - 15 + 5 * 2;
-        return null; // Replace null with the variable you used to store the result
+        Integer answer = 48 - (15 + 5) * 2;
+        return answer; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -226,9 +246,9 @@ public with sharing class VariablesDataTypesOperators {
      */
     public static Double complexOrderOfOperations(Integer a, Integer b, Integer c, Integer d, Integer e) {
         // Add parentheses around the multiplication and subtraction operations so that they are performed before division and addition
-        Double result = a * b - c / (Double) d + e;
+        Double result = (a * b - c) / (Double) d + e;
 
-        return null; // Replace null with the variable you used to store the result
+        return result; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -242,8 +262,10 @@ public with sharing class VariablesDataTypesOperators {
         final Double SUBTRACT_FACTOR = 32.0;
         final Double MULTIPLY_FACTOR = 5.0;
         final Double DIVIDE_FACTOR = 9.0;
+
+        Double celciusTemp = (fahrenheit - SUBTRACT_FACTOR) * (MULTIPLY_FACTOR / DIVIDE_FACTOR);
 
-        return null; // Replace null with the variable you used to store the result
+        return celciusTemp; // Replace null with the variable you used to store the result
     }
 
 
@@ -259,11 +281,11 @@ public with sharing class VariablesDataTypesOperators {
      */
     public static Integer performDivisionAndCast(Double a, Double b) {
         // Perform the division and cast (round down) off the result.
-        Double divisionResult = null;
+        Double divisionResult = a / b;
 
         // Write the code for type casting the divisionResult to an Integer
-        Integer roundedResult = null;
-        return null; // Replace null with the variable you used to store the result
+        Integer roundedResult = (Integer) divisionResult;
+        return roundedResult; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -277,7 +299,8 @@ public with sharing class VariablesDataTypesOperators {
      */
     public static Decimal calculateWeeklyPaycheck(Decimal hourlyRate, Double numberOfHours) {
         // Calculate the weekly paycheck using the formula: rate multiplied by hours
-        return null; // Replace null with the variable you used to store the result
+        Decimal weeklyPaycheck = hourlyRate * numberOfHours;
+        return weeklyPaycheck; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -291,7 +314,8 @@ public with sharing class VariablesDataTypesOperators {
      * @return A Decimal representing the monthly paycheck.
      */
     public static Decimal calculateMonthlyPaycheck(Decimal hourlyRate, Double numberOfHours) {
-        return null; // Replace null with the variable you used to store the result
+        Decimal monthlyPaycheck = hourlyRate * numberOfHours * 4;
+        return monthlyPaycheck; // Replace null with the variable you used to store the result
     }
 
     /**
@@ -305,6 +329,7 @@ public with sharing class VariablesDataTypesOperators {
      * @return The total cost after applying the sales tax.
      */
     public static Decimal calculateTotalCost(Decimal pricePerUnit, Integer numberOfUnits, Decimal salesTaxRate) {
-        return null; // Replace null with the variable you used to store the result
+        Decimal totalCostWithTax = (pricePerUnit * numberOfUnits) * (1 + salesTaxRate);
+        return totalCostWithTax; // Replace null with the variable you used to store the result
     }
 }