First we have to find the price per case.
We can do this by dividing 408 by 17, because we know that 17 cases cost 408 and each case will cost the same.
408/17= 24
Now we can find the price of the five cases they want to add.
24 X 5 = 120
Now we just add that price back to original order price.
408 + 120 = 528
