The Sum of Two Numbers is 40 and Their Difference is 15

The sum of two numbers is 40 and their difference is 15. 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 40. In other words, x plus y equals 40 and can be written as equation A:

x + y = 40

The difference between x and y is 15. In other words, x minus y equals 15 and can be written as equation B:

x - y = 15

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

x - y = 15
x = 15 + y

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

x + y = 40
15 + y + y = 40
15 + 2y = 40
2y = 25
y = 12.5

Now we know y is 12.5. Which means that we can substitute y for 12.5 in equation A and solve for x:

x + y = 40
x + 12.5 = 40
X = 27.5

Summary: The sum of two numbers is 40 and their difference is 15. What are the two numbers? Answer: 27.5 and 12.5 as proven here:

Sum: 27.5 + 12.5 = 40
Difference: 27.5 - 12.5 = 15

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The Sum of Two Numbers is 40 and Their Difference is 16
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