If n books cost r rupees. Then how much will m books cost?

Explanation

If n books cost r rupees, you can find the cost of m books using the concept of proportionality. The cost of books is directly proportional to the number of books. The proportionality constant is the cost per book. Let c be the cost of one book. So, n books cost r rupees can be written as: n.c=r Now, to find the cost of m books, set up the proportion: n/m=r/x Where x is the cost of m books. Cross-multiply to solve for x: n . x= m. r Now, divide both sides by n to find the cost of one book (c): x=mr/n