Ok, I'll make it simple for you: Keep Change Change. For all subtraction problems (and only subtraction, no addition), all you have to do is keep the first number, then change the sign from a minus to a plus, and then change the last number to the opposite. For example: 7 - (-3) 7 + 3=10
-4 - 10 -4 + -10= -14
For addition, if both numbers are negative, you just add them together. For example: -21 + (-13)= -34
In this case you switch the sign and the number's sign also: 7 + (-18) 7 - 18 = -11
