A family wishes to provide an annuity of $100 at the end of each month to their daughter now entering college. The annuity will be paid for only nine months each year for four years. 求 the present value one month before the first payment.
请问这题怎么理解啊 这里的“一年中的九个月”是什么意思,给女儿的是每年12次吗?