If 4 gallons of gasoline are added to a tank that is already filled to 3/4 of its capacity, the tank is then filled to 9/10 of its capacity. How many gallons does the tank hold?
Choose the correct option.
A) 20  B) 24  C) 36  D) 40  E) 60

Rationale: "let the capacity of the tank = c ( 3 / 4 ) c + 4 = ( 9 / 10 ) c = > ( 9 / 10 ) c - ( 3 / 4 ) c = 4 = > ( 3 / 20 ) c = 4 = > c = ( 4 * 20 ) / 3 = 26.66 number of gallons of gasoline that the tank currently holds = 3 / 4 * c + 4 = 19.99 + 4 = 23.99 = 24 answer b"
Answer: B