Answer
$27 \text{ gal}$
Work Step by Step
Convert by multiplying $\dfrac{1 \text{ gal}}{231 \text{ in.}^3}$ to obtain:
$=\require{cancel}
6237 \cancel{\text{ in.}^3} \cdot \dfrac{1\text{ gal}}{231 \cancel{\text{ in.}^3}}
\\=\dfrac{6237}{231} \text{ gal}
\\=27 \text{ gal}$