If x 80% of y, then what percent of 2x is y ?

Answer: Option B

x = 80% of y
⇒ x = $$\frac{80}{100}$$y
⇒ $$\frac{y}{x}$$ = $$\frac{5}{4}$$
⇒ $$\frac{y}{2x}$$ = $$\frac{5}{8}$$
∴ Required percentage :
$$\begin{array}{rl}& =\left(\frac{y}{2x}\times 100\right)\%\\ & =\left(\frac{5}{8}\times 100\right)\%\\ & =62\frac{1}{2}\%\end{array}$$