What the problem is trying to show you, is that a positive number undoes a negative number and a negative number undoes a positive number meaning it changes it's value.
If I get 4 (positive number) and subtract it by 4 the answer will be 0 - the negative number -4 undid the number 4.
If I get -4 (negative number) and add 4 (positive number) the answer will be 0 - meaning the positive number 4 undid the number -4.
Hope it helped,
BioTeacher101
Curtis runs at 7 mph. Marsy runs at 8 mph.
In opposite directions, they separate at 15 mph.
After 2 hours, they're 30 miles apart.
