PREP DS1 215求教(已解决)

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,我选C.

根据1,2完全可以计算啊,过程如下:

2 items was paid 510-480=30, 所以超过36个每个15,不超过36的每个10.

480=36*10+15x =>x=8

所以last week Bob produced 36+8=44 items.

我的计算有什么问题吗??

感谢Elutitti 指教!

少考虑了一种情况,就是两周都没有超过36,即x=15.

last week 32*15
this week 34*15

所以选E.

又被gmat给耍了,郁闷啊!