帮忙解答下这几道PS题

liptontea

1. A merchant purchased a jacket for $60 and hten determined a selling price that equalled the purchase price of the jacket plus a markup that was 25 percent of the selling price. During a sale, the merchant discounted the selling price by 20 percent and sold the jacket. What was the merchant's gross profit on this sale?
A. $0
B. $3
C. $4
D. $12
E. $15

2. Ben and Ann are among 7 contestants from which 4 semifanilists are to be selected. Of the different possible selections, how many contain neither Ben nor Ann?
A. 5
B. 6
C. 7
D. 14
E. 21

the key: 1. C, 2. A

多谢指教！

夏日飘雪

第一题，假设没有打折时准备卖的价格为X则
60+0.25X=X
X=80
打折了，则80*0.8=64
则profit: 64-60=4

第二题
组合题，C(4,5)=5

话说我大后天就上战场被宰了。。。。5555。。。。希望RP不要太差就行了。。

liptontea

多谢帮忙解答。

感觉你数学很好，应该可以得满分。偶还要继续加油累！

预祝你杀G成功！