A Piper Warrior Holds 50 Gal of 100LL Aviation Fuel $15$

A Piper Warrior holds 50 gal of 100LL aviation fuel. A pilot takes off and lands at another airport and fills up the tank, which takes $15$ gal. The pilot then flies to a second airport, which requires $21 \frac { 3 } { 8 }$ gal. Had the pilot made the trip to the two airports without refueling each time, how much fuel would have been left in the tank?

A) $13 \frac { 1 } { 3 }$ gal
B) $14 \frac { 1 } { 3 }$ gal
C) $13 \frac { 1 } { 8 }$ gal
D) $13 \frac { 3 } { 8 }$ gal
E) $14 \frac { 1 } { 8 }$ gal