Cost price of radio = Rs.225
Overhead expenses = Rs. 15
Total cost = cost price + overhead expenses = 225+15 = Rs. 240
Selling price of radio = Rs.300
Gain = 300 – 240 = Rs. 60
= Gain % = \(\frac{gain}{cost\,price}\)x 100 = \(\frac{60}{240}\)x 100 = 25 %