请教一个prep的数学问题

danielgc

PS.
At a certain supplier, a machine of type Acosts $20,000 and a machine of type B costs $50,000.  Each machine can be purchased by making a 20percent down payment and repaying the remainder of the cost and the finance chargesover a period of time.  If the financecharges are equal to 40 percent of the remainder of the cost, how much lesswould 2 machines of type A cost than 1 machine of type B under thisarrangement?

A.10000
B.11200
C.12000
D.12800
E.13200

robinyue

我个人的答案是E……不知道对不对
个人对于题目的理解：先付20%的首付，剩下来有80%，但是还需要在剩下的基础上多交40%的费用。
于是乎这样列式——
(50000-2*20000)*80%*(1+40%)+(50000-2*20000)*20%=11200+2000=13200

sogapink

repaying the remainder of the cost：
比如A的话，到时候再付A的cost（也就是20000）剩下的80%（也就是16000）

triangel8866

同求啊，repaying the remainder of the cost 是什么意思啊？