15. If $15 \%$ of $x$ equals $20 \%$ of $y$, then $y$ is what percent of $x$?
(A) 5
(B) 35
(C) 75
(D) $133 \frac{1}{3}$
(E) 300
15. C.

From the given, we have $0.15 x=0.20 y$.
Then $\frac{y}{x}=\frac{15}{20}=\frac{75}{100}$.