Hugh bought some magazines that cost $3.95 each and some books that cost $8.95 each. he spent a total of $47.65. if hugh bought 3 magazines, how many books did he buy? the equation that models the problem is 3.95m + 8.95b = 47.65, where m is the number of magazines and b is the number of books.

So first you want to find the price of all the magazines he bought which is 3.95 x 3 = 11.85.
then you are going to find out how much money he had left to spend on books which is 47.65-11.85=35.80 

then you want to find how many books he bought with that money so you would take 35.80/8.95= 4

so he bought 4 books

Are you trying to figure out the volume?