Suppose $20 \textbackslash\%$ of $x$ equals $40\textbackslash\%$ of $y$. What percentage of $y$ is $x$ ? (adapted from 2020 AMC 8, Question 15) 
选项为:A:$$35$$  B:$$50$$  C:$$75$$  D:$150$  E:$$200$$  请回答其中一个选项.