Can you answer or give me an equation that i can solve for numbers 18,17,16,15 thx

15) If you only need a cup of milk, you should go for the smallest option (ie. container w/ least amount of cup equivalents). This would be pint

16)First convert cups of OJ to quarts. This will be 2 quarts. There will be 6 more quarts of lemon juice than OJ

17) First, you must convert all the measurements to the same thing. Since we've already converted OJ to quarts in the previous problem, all you have to do is convert the pints of ice cream to quarts as well. 4 pints is 2 quarts. 
So we add 2 + 2 + 8 = 12 quarts total

12 quarts is equal to 3 gallons of punch