You can solve this via algebra, lets say the numbers are x and y.
x + y = 43 and x - y = 19
You can re-arrange one of the equations to get
x = 43 - y Then substitute this into the other equation, so instead of x you put this:
(43 - y) - y = 19
43 - 2y = 19
-2y = 19 - 43
-2y = -24
-y = -12
so y = 12
then you can do 43 - 12 = 31 to get both of the numbers.
so the numbers are 31 and 12
