
Evan M. answered 03/04/20
Software Engineer with an M.S. in Structural Engineering
This is how I am interpreting your question:
Sum of two numbers is 11, Difference of two numbers is 5. What are the numbers.
Let x equal the first number, and y equal the second number. We can write two equations:
x + y = 11
x - y = 5
If we sum both equations (vertically), we get:
(x + x) + (y + -y) = (11 + 5)
This simplifies to 2x = 16, so x = 8.
Now we can plug 8 back into either equation to solve for y:
8 + y = 11
y = 3