Dear SailorMars, #4's question is very convoluted so I won't show you how to do it. Luckily, I do know how to do #5 and #6. With #5, multiply 8 5/6 by two to get 17 2/3, then do 50-17 2/3 to get 32 1/3 ft of tape. With #6, add 11 1/2 and 6 4/5 to get 18.3 gallons of gas, then do 18.3-3 3/10 to get 15 gallons of gas used.