There are 20 guests at a party. the host has 8 gallons of punch. he estimates that each guest will drink 2 cups of punch. if his estimate is correct, how much punch will be left over at the end of the party?

Its correct. Im pretty sure the way to solve it is. 16 cups in 1 gal. Then do 8x16 to find the total amount of cups...Then do 20x2 for the 2 cups each person will have which gives you 40 then do 128(total of 16x8)-40(amount of cups that they drank) and you should get...88 cups left