The Sum of Two Numbers is 9 and Their Difference is 7

The sum of two numbers is 9 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 9. In other words, x plus y equals 9 and can be written as equation A:

x + y = 9

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 = 9
7 + y + y = 9
7 + 2y = 9
2y = 2
y = 1

Now we know y is 1. Which means that we can substitute y for 1 in equation A and solve for x:

x + y = 9
x + 1 = 9
X = 8

Summary: The sum of two numbers is 9 and their difference is 7. What are the two numbers? Answer: 8 and 1 as proven here:

Sum: 8 + 1 = 9
Difference: 8 - 1 = 7

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The Sum of Two Numbers is 9 and Their Difference is 8
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