The shampoo you like to use is on sale. But you only get the lower price if you buy 3 bottles. You want to know how much you'll
save. Write a formula that will help you determine how much you'll save by buying 3 bottles
on sale.
Let's let
s = sale price per bottle
r = regular price per bottle
c = cost savings
If you want to get the lower price down you are going to have to buy 3 shampoo bottles in order to get a lower price. The cost you save is the main difference from a regular price. And the answer is c = 3r - 3s