when we do the additive inverse property...we want to end up with a 0...so the inverse of 7 is -7 and the inverse of -8 is +8....we now have our new expression
-7 + 8
-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
