When adding integers, the signs must be the same. Add the numbers and keep
the sign.
-2 + -7 = -9
If the signs are different, do a "take away" and keep the sign of
the "larger" number.
4 + -6 = -2
When multiplying integers, count the number of negative signs.
If there is an even number of negative signs the answer will be positive.
(-2)(7)(-3) = 42
If there is an odd number of negative signs, the answer will be negative. (8)(-3)(5)
= -120