Let's use x and y for the numbers.
Difference means we are subtracting, so we know:
x - y = 36
Sum means we are adding, so we know:
x + y = 12
Now we can use substitution to solve. In the first equation, we can solve for x by subtracting y:
x = y + 36
Now plug y+36 in for x in the second equation.
(y+36) + y = 12
2y + 36 = 12
2y = -24
y = -12
Now plug -12 in for y to find x.
x + (-12) = 12
x = 24
So the numbers are 24 and -12