Which is the better buy for processed cheese slices, 8 slices for $2.19, or 12 slices for $3.30?

Question

Its a math problem I went over in class but don't understand on the test

Answer 1

You need to compute the unit rate (unit price) for each case.  The unit price is the price of 1 slice of cheese:

 

Unit Price 1 = $2.19/8 slices = ____________

 

Unit Price 2 = $3.30/12 slices = ____________

 

Complete the divisions to determine each unit price.  The lower unit price is the better buy.