Answer
12$\frac{1}{8}$ gal
Work Step by Step
Let piper warrior hold 50 gal of aviation fuel, it use 17$\frac{1}{2}$ gal and 20$\frac{3}{8}$ gal of aviation fuel to reach the first and second location respectively
Therefore total aviation fuel left= 50 gal - 17$\frac{1}{2}$ gal - 20$\frac{3}{8}$ gal
= 50 - $\frac{35}{2}$ - $\frac{163}{8}$
= 50 $\times$ $\frac{8}{8}$- $\frac{35}{2}\times$ $\frac{4}{4}$- $\frac{163}{8}$
=$\frac{400}{8}$ - $\frac{140}{8}$ + $\frac{163}{8}$
= $\frac{97}{8}$
= 12$\frac{1}{8}$ gal
