Respuesta :
There is 16 cups in one gallon, so 16x8=128. so 128-40=88. 88/16=5.5 so there is 5.5 gallons of punch left.
3 gallons would be left over because each guest will drink 16 ounces which for 20 people is 320 ounces. 8 gallons is 512 ounces so subtract what the people drank which was 320 ounces which leaves 192 ounces which is equal to 3 gallons