The list price of a book is $15. But if more than 12 copies are purchased, then the price per copy is reduced by $0.20 for every copy above 12. That is, $14.80 per copy for 13 copies, $14.60 per copy for 14 copies, and so on.
How much do you save by buying 24 copies than if you bought 2 sets of 12?

Question

The list price of a book is $15. But if more than 12 copies are purchased, then the price per copy is reduced by $0.20 for every copy above 12. That is, $14.80 per copy for 13 copies, $14.60 per copy for 14 copies, and so on. 
How much do you save by buying 24 copies than if you bought 2 sets of 12?

ivettef365 · Answer

first calculate how much is a set of 12 copies and multiply by 2

ivettef365 · Answer

then you have that after the 13th copy it will lower .20 cents, if you buying 24, then you have 24 - 12 = 12, then it would be a deduction of .20 x 12 = 2.40 per copy, so for 24 copies you pay 12.60/per copy