So if you let x and y be the two numbers...
the sum of the two means you add them together... so you get:
x+y=56 : the difference means you subtract them.. so
x-y = 16
now you have two equations and two unknowns... which you can solve with a variety of methods... you can use elimination, substitution, or trial and error.
x+y=56
x-y = 16
I will use the elimination method: Because there is a plus y and a negative you cancel that out and you add the 2x's. Therefore:
2x=72
x=36
Now, you can plug in 36 into one of your original equation:
36+y=56
y=20
Those are your two numbers!
