He has $500 to start with, and he takes $25 out of the account each week. But he wants more than 200 in his account by the end of summer. 25 goes into 500 20 times. But if he wanted more than 200 left, like 300-400, he could spend 4 week's worth of money to have 400 left, or 8 weeks to have 300 left. This is the best-case scenario.
