The Sum of Two Numbers is 30 and Their Difference is 4

The sum of two numbers is 30 and their difference is 4. 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 30. In other words, x plus y equals 30 and can be written as equation A:

x + y = 30

The difference between x and y is 4. In other words, x minus y equals 4 and can be written as equation B:

x - y = 4

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

x - y = 4
x = 4 + y

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

x + y = 30
4 + y + y = 30
4 + 2y = 30
2y = 26
y = 13

Now we know y is 13. Which means that we can substitute y for 13 in equation A and solve for x:

x + y = 30
x + 13 = 30
X = 17

Summary: The sum of two numbers is 30 and their difference is 4. What are the two numbers? Answer: 17 and 13 as proven here:

Sum: 17 + 13 = 30
Difference: 17 - 13 = 4

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The Sum of Two Numbers is 30 and Their Difference is 5
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