If 50% of (p - q) = 30% of (p + q), then p : q is equal to?

Answer: Option B

$$\begin{array}{rl}& 50\%\text{ of }\left(p-q\right)=30\%\text{ of }\left(p+q\right)\\ & \frac{p-q}{2}=\frac{3}{10}\left(p+q\right)\\ & \left[50\%=\frac{1}{2}\right]\\ & \Rightarrow 5\left(p-q\right)=3\left(p+q\right)\\ & \Rightarrow 5p-5q=3p+3q\\ & \Rightarrow 2p=8q\\ & \Rightarrow 1p=4q\\ & \Rightarrow p:q=4:1\end{array}$$