The simple rule is to change subtraction problems into addition

problems. I mean it. To subtract a number you just add its

opposite. Change all the subtraction symbols to

addition symbols. Then change the sign of the number that

followed the original subtraction symbol.

Here's an example:

7 - (-4) = ?

If we change this to an addition problem, we now have:

7 + 4 = 11

We changed the subtraction symbol to addition and we changed

the negative four to a positive four. Then use the rules for addition

found on page one.

-8 - (9) = ? becomes -8 + (-9) = -17

-10 - (-7) = ? becomes -10 + 7 = -3

98 - 64 = ? becomes 98 + (-64) = 34