Since $20 \textbackslash\%=\frac{1}{5}$, multiplying the given condition by 5 shows that $y$ is $15 \cdot 5=(\mathbf{C}) 75$ percent of $x$. 
Suppose $15 \textbackslash\%$ of $x$ equals $20 \textbackslash\%$ of $y$. What percentage of $x$ is $y$ ? (2020 AMC 8, Question 15) 
A. $$5$$ 
B. $$35$$ 
C. $$75$$ 
D. $133\frac{1}{3}$ 
E. $$300$$ 