Question

A publisher sells either digital copies of their new book, paperback copies or hardback copies. For every 4 digital sales they make, they make 5 paperback sales and 1 hardback sale. In the first week of sales, the company sells 308 more paperback copies of the book than hardback copies.

Answer 1

This means in the first week the number sells of digital copies is 308, paperback sells was 385 copies and hardback sell was 77 copies

Explanation:

Let the number of digital copies be x, the number of paperback copies be y and the number of hardback copies be z.

4 digital sales is equal to 5 paperback sales and 1 hardback sale.

5x = 4y, x = 4z, y = 5z

The company sells 308 more paperback copies of the book than hardback copies

y = 308 + z

But y = 5z

5z = 308 + z

4z = 308

z = 77

y = 5z = 5(77) = 385

x = 4z = 4(77) = 308

This means in the first week the number sells of digital copies is 308, paperback sells was 385 copies and hardback sell was 77 copies