A man buys some articles at Rs. P per dozen and sells them at Rs. P8 per price. His profit percent is = ?

Answer: Option C

According to the question,
Cost price of 12 articles = Rs. P
Selling price of 1 article
$$=\text{Rs}\text{.}\frac{\text{P}}{8}$$
Selling price of 12 articles
$$\begin{array}{rl}& =\frac{\text{P}}{8}\times 12\\ & =\frac{3}{2}\text{P}\\ & \text{Profit}=\text{SP}-\text{CP}\end{array}$$
$$\begin{array}{rl}& =\frac{3\text{P}}{2}-\text{P}\\ & =\frac{3\text{P}-2\text{P}}{2}\\ & =\frac{\text{P}}{2}\end{array}$$
$$\begin{array}{rl}& \mathrm{Profit}\%=\frac{\text{P}}{\frac{2}{\text{P}}}\times 100\\ & =\frac{1}{2}\times 100\\ & =50\%\end{array}$$