The Sum of Two Numbers is 87 and Their Difference is 7

The sum of two numbers is 87 and their difference is 7. What are the two numbers? Let's start by calling the two numbers we are looking for x and y.

The sum of x and y is 87. In other words, x plus y equals 87 and can be written as equation A:

x + y = 87

The difference between x and y is 7. In other words, x minus y equals 7 and can be written as equation B:

x - y = 7

Now solve equation B for x to get the revised equation B:

x - y = 7
x = 7 + y

Then substitute x in equation A from the revised equation B and then solve for y:

x + y = 87
7 + y + y = 87
7 + 2y = 87
2y = 80
y = 40

Now we know y is 40. Which means that we can substitute y for 40 in equation A and solve for x:

x + y = 87
x + 40 = 87
X = 47

Summary: The sum of two numbers is 87 and their difference is 7. What are the two numbers? Answer: 47 and 40 as proven here:

Sum: 47 + 40 = 87
Difference: 47 - 40 = 7

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