请教prep数学一题

hijiguo

At a certain supplier, a machine of type A cost $20,000 and a machine of type B cost $50,000. Each machine can be purchased by making a 20% down payment and repaying the remainder of the cost and the finance charges over a period of time. If the finance charges are equal to 40% of the remainder of the cost, how much less would 2 machines of type A cost than 1 machine of type B under this arrangement.

The answer is 13,200.


我的计算: 1)repaying the remainder算2次的话: (50,000-20,000*2)*(1+20%+20%*40%)=12,800.
2)如果repaying只算一次：(50,000-20,000*2)*(1+20%*40%)=10,800.


怎么都算不到13,200...请教大家。谢谢先

gmatbenben

Machine A:
2*20000*(1-20%)*40%+2*20000=52 800

Machine B:
1*50000*(1-20%)*40%+1*50000=66 000

52800 - 66000 = -13200

hijiguo

20% down payment 是预付。。。我开始以为预付80%。。。明白了。谢谢