Awater tank holds 18,000 gallons how long will it take for the water level to reach 6,000 gallons if the water is used at an average rate of 450 gallons per day?

Well, it won't exactly be 6000 gallons because It's taking away 450 gallons per day.  My answer is 26 days. in which there are still 6300 gallons. But if you want to add one more day then you would have 5850.

9/12 is the answer because 3/4 times 3 each is 9/12