Answer
$P=18\frac{x}{y^2}$
Work Step by Step
$P=k\frac{x}{y^2}$
$P=\frac{28}{3}$ when $x=42$ and $y=9$:
$\frac{28}{3}=k\frac{42}{9^2}=k\frac{42}{81}$
$k=\frac{\frac{28}{3}}{\frac{42}{81}}=\frac{28}{3}\frac{81}{42}=\frac{2268}{126}=18$
Then:
$P=18\frac{x}{y^2}$
