Question. Phil has a coin collection he likes to add to. He started with 50 state quarters his parents gave him. Over the next year he doubled this. The following year he collected 3 each month. The year after that he collected 1 every third month. The year after that he lost a quarter of them when he misplaced his collection. How many did he have left after losing some?
Answer. 105
What step-by-step reasoning justifies that answer?
Reasoning: Phil started with 50, and doubled this amount the next year for 50 * 2 = 100 coins. Phil then collected 3 per month the following year, and since there are 12 months in a year that was 3 * 12 = 36 coins added. Phil then collected 1 every third month, and since there are 12 months that means he collected one every 12 / 3 = 4 months, for 4 coins added. Before he lost a quarter of his coins, Phil had 100 + 36 + 4 coins, or 140 coins in total. Losing a quarter of 140 coins means Phill lost 140 / 4 = 35 coins. That means Phil had 140 - 35 = 105 coins remaining.