求PREP-DS-1-215 （已解决）

215.
    20843-!-item-!-187;#058&013306

If Bob produces 36 or fewer items in a week, he is paid x dollars per item.  If Bob produces more than 36 items in a week, he is paid x dollars per item for the first 36 items and 1.5 times that amount for each additional item.  How many items did Bob produce last week?

(1) Last week Bob was paid a total of $480 for the items that he produced that week.

(2) This week Bob produced 2 items more than last week and was paid a total of $510 for the items that he produced this week.

答案: E

但是我怎么算出C来了呢

思路如下:

如果多2 items=510-480 

那么，1 item= 15

若此时１５元／个的定价是　少于３６的情况，那么Ｘ＝１５，但１５＊３６＝４８０，因此不可能为少于３６的情况，

则，1.5X=15, X=10

若 X=10,

480=36*10+ 15*Y (Y为比36多出来的个数)

Y=8

则一共做了36+8=44 个

.....

这个思路到底错在哪里了呢?

思路是对的，只是由于15*36=540， 15*32=480. 所以第一种情况是可能的

汗死．．．

计算错误．．．

可以去撞墙了．．．．

谢谢