A man purchases some oranges at the rate of 3 for Rs. 40 and the same quantity at 5 for Rs. 60. If he sells all the oranges at the rate of 3 for Rs. 50, find his gain or loss percent ( to the nearest integer ) = ?

Answer: Option D

Man purchased 15 oranges of each type
CP of 1^st type $$=\frac{40}{3}\times 15=200$$
CP of 2^nd type $$=\frac{60}{5}\times 15=180$$
Total cost price = (200 + 180) = 380
Total selling price $$=\frac{50}{3}\times 30=500$$
∴ Profit percentage
$$\begin{array}{rl}& =\frac{500-380}{380}\times 100\\ & =\frac{120}{380}\times 100\\ & =\frac{600}{19}\%\\ & =31.57\%\\ & \approx 32\%\end{array}$$