Amy bought a 15-foot spool of string to cut up into wicks for making candles.  If she cuts up the entire string into an equal number of 6-inch and 12-inch wicks, what is the total number of wicks she will have cut? Let's answer step by step:
15 feet of string is 15 * 12 = 180 inches long. If for every 6 - inch wick she also cuts a 12 - inch wick, then the pair of wicks are 6 + 12 = 18 inches long. Thus, in 180 inches of string, she can cut 180 / 18 = 10 pairs of wicks. 10 pairs of wicks are a total of 10 * 2 = 20 wicks. The answer: 20.