`120` copies of a book cost is `600` rs cost of `400` copies will be what

120 copies of a book cost Rs 540. what will 400 copies of this book cost?

A publisher printed 2000 copies of a book at a cost of Rs 70,000. He distributes 400 copies free as specimen copies . He gave 30% discount on printed price and the printed price of each book is Rs 75. What is his gain or loss percentage?

If the cost price of 21 copies of a book,are the same as the selling price of 18 copies of the book,then gain percent is

The cost of 5 books is Rs. 40. What is the cost of 7 books?