The Sum of Two Numbers is 9 and Their Difference is 3

The sum of two numbers is 9 and their difference is 3. 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 3. In other words, x minus y equals 3 and can be written as equation B:

x - y = 3

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

x - y = 3
x = 3 + y

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

x + y = 9
3 + y + y = 9
3 + 2y = 9
2y = 6
y = 3

Now we know y is 3. Which means that we can substitute y for 3 in equation A and solve for x:

x + y = 9
x + 3 = 9
X = 6

Summary: The sum of two numbers is 9 and their difference is 3. What are the two numbers? Answer: 6 and 3 as proven here:

Sum: 6 + 3 = 9
Difference: 6 - 3 = 3

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The Sum of Two Numbers is 9 and Their Difference is 4
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