Problems 6-17
Copy down the problem as you see it in the book, and then carry out
the order of operations as described by the first 
sign in this section. You will find it easier if your organize your
work as shown here (for Problem 15a):
8 + 2(3 + 12) - 5 * 3 = 8 + 2(15) - 15 * 3
= 8 + 30 - 45
= -7