Tim’s bathtub contains 75 gallons of water. Tim is draining water from the tub at a rate of 1.5 gallons per minute. If Tim wants to keep at least 20 gallons of water in the tub, which inequality could be used to determine the number of minutes he will need to drain the water?
A.75 + 1.5x ≤ 20
B.75 – 1.5x ≤ 20
C.75 + 1.5x ≥ 20
D. 75 – 1.5x ≥ 20