It's a good idea to get into the habit of
using parenthses when substituting
numbers in for variables.
Since x = -4 and y = -2, 5x - y is 5(-4) - (-2).
Now, 5(-4) is -20 and minus a negative 2
can be thought of as plus a positive 2.
So we have (-20) + (+2) which equals -18.
