Answer:
1090miles/gallon approximately
Explanation:
On average a Sedan tank can hold 18.5 gallons.
If it's 75% full, it means it is 18.5 x 0.75 = 13.875 gallons full.
Since the number of miles covered was recorded as 15121 with 75% full gas tank, then to determine mile/gallon can be found by
15121/13.875 ≈ 1090miles/gallon