The Sum of Two Numbers is 77 and Their Difference is 4

The sum of two numbers is 77 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 77. In other words, x plus y equals 77 and can be written as equation A:

x + y = 77

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 = 77
4 + y + y = 77
4 + 2y = 77
2y = 73
y = 36.5

Now we know y is 36.5. Which means that we can substitute y for 36.5 in equation A and solve for x:

x + y = 77
x + 36.5 = 77
X = 40.5

Summary: The sum of two numbers is 77 and their difference is 4. What are the two numbers? Answer: 40.5 and 36.5 as proven here:

Sum: 40.5 + 36.5 = 77
Difference: 40.5 - 36.5 = 4

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The Sum of Two Numbers is 77 and Their Difference is 5
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