Question

A book store sells used books. Paperback books cost $1.00. Hardback books sell for $5.00. The store sold 100 books and made $260 from the sale, How many paperback books did the store sell?

Answer 1

60 paperback books

Step-by-step explanation

We have that:

Paperback books sell for $1.00

Hardback books sell for $5.00

The store sold 100 books and made $260.

Let the number of paperback books be x

Let the number of hardback books be y.

This means that:

x + y = 100 _____(1)

and

1 * x + 5 * y = 260

=> x + 5y = 260 ____(2)

We have two simultaneous equations:

x + y = 100 ____(1)

x + 5y = 260 ___(2)

From (1):

x = 100 - y

Put that in (2):

100 - y + 5y = 260

=> 100 + 4y = 260

Collect like terms:

4y = 260 - 100

4y = 160

y = 160 / 4

y = 40 books

This means that:

x = 100 - 40

x = 60 books

Therefore, 60 paperback books were sold.