Frank spent 1/5 of his money to buy groceries. He then spent 1/4 of the remaining money to buy a magazine. If he had $360 left in his wallet, how much money did he have at first? Let's be accurate as possible.
Let X be the money Frank had originally. Frank spent 1 / 5 * X on groceries. Frank spent 1 / 4 * (X - 1 / 5 * X) on a magazine. Frank has X - 1 / 5 * X - 1 / 4 * (X - 1 / 5 * X) = $360 left in his wallet. Multiplying through the parentheses, we get X - 1 / 5 * X - 1 / 4 * X + 1 / 20 * X = $360. Combining like terms, we get 12 / 20 * X = $360. Dividing both sides by 12 / 20, we get X = $600.
The answer: 600.