A publisher printed 2000 copies of a book at a cost of Rs. 70000. He distributes 400 copies free as specimen copies. He gave 30% discount on marked price of each book which is Rs. 75. What is his gain or loss percentage = ?

Answer: Option A

According to the question,
Cost price of 2000 books are = Rs. 70000
Cost price of 1 book is $$=\frac{70000}{2000}=\text{Rs}\text{. 35}$$
Marked price of 1 book is = Rs. 75
Discount = 30%
Selling price of 1 book = Rs. 52.5
He distribute 400 books free
Selling price of 1600 books = 52.5 × 1600
= Rs. 84000
Profit = Selling price - Cost price
= 84000 - 70000
= Rs. 14000
$$\begin{array}{rl}& \text{Profit }\%=\frac{14000}{70000}\times 100\\ & =20\%\text{ gain}\end{array}$$