[" If the cost of "15" books is "₹90," then what is the cost "],[" of one book? "]

If the cost of 15 books is Rs90, then what is the cost of one book?

The cost of 10 books is ₹ p. what is the rule for the cost of one book.

The cost of one book is ₹ 13, then what is the rule for the cost of ‘n’ books.

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

The rule for purchase of books is that the cost of q books is ₹23, then find the price of one book?

If the cost of 12 books is Rs 144, then the cost of 18 books is (a) Rs 206 (b) Rs 216 (c) Rs 198 (d) Rs 180

If the cost of 12 books is Rs 144, then the cost of 18 books is (a) Rs 206 (b) Rs 216 (c) Rs 198 (d) Rs 180