57、DS: somebody invested 17,000, interest rate x% simply rate and have Z dollor interest, what would he have to invest in a account which has y% interest rate, simple rate so that he can have same interest. A. X=2 B Y=50%X
SA: B
想问dollar interest是不是应有时间在内啊？dollar interest=principal*interest rate*time,1年和2年拿到的dollar interest应该不一样多啊。 | 
