Suppose $15 \textbackslash\%$ of $x$ equals $20 \textbackslash\%$ of $y$. What percentage of $x$ is $y$ ? (2020 AMC 8, Question 15) 
选项为:A:$$5$$  B:$$35$$  C:$$75$$  D:$133\frac{1}{3}$  E:$$300$$  请回答其中一个选项.