Jason spent 1/4 of his money and an additional $10 on some books. He then spent 2/5 of the remaining money and an additional $8 on some DVDs. If he was left with $130, how much money did he have at first? Think carefully first, then make a decision:
Let X be the money Jason had at first. Jason spent 1 / 4 * X + 10 on books. Jason spent 2 / 5 * [X - (1 / 4 * X + 10)] + 8 on some DVDs. Jason has X - (1 / 4 * X + 10) - {2 / 5 * [X - (1 / 4 * X + 10)] + 8} = $130 left. X - 1 / 4 * X - 10 - 2 / 5 * X + 1 / 10 * X + 4 - 8 = $130. 9 / 20 * X - 14 = $130. X = $320. So, the answer is 320.