(a)Find the total number of calendar he has originally.
更新1:
(b)Suppore the bookseller can only sell a further 100 calendar after the price reduction, and then discard all the remaining calendar.Find the total cost of the calendar if the overall profit percent is 20% 跟上題ga ~~ thx~~^^
更新2:
the answer is $6500,,,but i don't know the example.....