Subtracting a negative number is the same as adding the positive.
The answer may be positive or negative depending on the size of the numbers.
Examples
15 - -21 = 15 + 21 = 36
-117 - -30 = -117 + 30 = -87
Remember
-11 + 3
is the same as
3 + -11
which is the same as
3 - 11
which is -8
These rules are really important to learn, so make sure you know them!
Let's try some questions now.