The cost price of a radio is Rs. 600. The 5% of the cost price is charged towards transportation. After adding that, if the net profit to be made is 15%, then the selling price of the radio must be = ?

According to the question,
Cost price of the radio = Rs. 600
5% of cost price is charged
$$\eqalign{ & = \frac{5}{{100}} \times 600 \cr & = {\text{Rs}}{\text{. 30}} \cr} $$
∴ Total cost price = 600 + 30 = Rs. 630
To gain 15% then selling price
$$\eqalign{ & = 630 + \frac{{15}}{{100}} \times 630 \cr & = {\text{Rs}}{\text{. 724}}{\text{.50}} \cr} $$