The Sum of Two Numbers is 4 and Their Difference is 5

The sum of two numbers is 4 and their difference is 5. 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 4. In other words, x plus y equals 4 and can be written as equation A:

x + y = 4

The difference between x and y is 5. In other words, x minus y equals 5 and can be written as equation B:

x - y = 5

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

x - y = 5
x = 5 + y

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

x + y = 4
5 + y + y = 4
5 + 2y = 4
2y = -1
y = -0.5

Now we know y is -0.5. Which means that we can substitute y for -0.5 in equation A and solve for x:

x + y = 4
x + -0.5 = 4
X = 4.5

Summary: The sum of two numbers is 4 and their difference is 5. What are the two numbers? Answer: 4.5 and -0.5 as proven here:

Sum: 4.5 + -0.5 = 4
Difference: 4.5 - -0.5 = 5

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The Sum of Two Numbers is 4 and Their Difference is 6
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