For a 35 pounds suitcase, the airline charges $0 for the first 20 pounds and $2 per pound for the remaining 15 pounds as the airline charges for only pounds over 20
He made 3.75 gallons. There was 1/10 remaining, meaning each tenth was 6 cups. The entire thing is 10 tenths so you do 6(10) to get 60 cups. After converting to gallons by doing 60÷26, you get 3.75.