[問題]Pre-P2-Ds 210

210. 20513-!-item-!-187;#058&013256

For each order, a mail-order bookseller charges a fixed processing fee and an additional shipping fee for each book in the order. Rajeev placed five different orders with this bookseller--an order for 1 book in January, an order for 2 books in February, an order for 3 books in March, an order for 4 books in April, and an order for 5 books in May. What was the total of Rajeev's processing and shipping fees for these five orders?

(1) Rajeev's processing and shipping fees were $1.00 more for his order in March than for his order in January.

 (2) The total of Rajeev's shipping fees for the five orders was $7.50.

ans:E

為什麼不是C啦  (1)+(2)不是可以解聯立了嗎？？？

我怎么觉着应选A呀，因为3（P+S）=1*（P+S）+1

P+S=1/2（P、S分别为加工费和运输费）

这样，1倍的P+S+2倍的。。。+3倍的。。。。+5倍的（P+S）=。。。。