This is darth vader and he demands that you me!

Carter drank 15.75 gallons of water in 4 weeks. he drank the same amount of water each day. a. estimate how many gallons he drank in one day. b. estimate how many gallons he drank in one week. c. about how many days altogether will it take him to drink 20 gallons?

Ingredient c: 1/4 cup for 2/3 serving or ingredient d: 1/3 cup for 3/4 serving which unit rate is smaller

What is the solution to the system of equations? y=1.5-3 y=-x