Explanation: If Josh paid for 3, 20 bills he would be paying $60, and if he got $16 in exchange you could subtract that from the amount he gave (60-16 = 44) then you would get how much all the books costs TOGETHER. But what you need to find is how much each book costs, you know they all cost the same and how much books he bought (4) so you just divide 44 by 4 which would get you 11.
