Alana and Petra go to a used book sale, where every book is the same price. Alana buys 5 books and Petra buys 4 books. They run into their friend Angus, who really loves to read, and discover that he has bought 19 books. Angus received a $10.00 discount, but he still spent $7.50 more than Alana and Petra combined. How much does one book cost?

Answer:

Cost of one book is $1.75.

Step-by-step explanation:

Let the cost of one book is $x.

Alana and Petra brought 5 + 4 = 9 books together.

⇒ Cost of book brought by them together is $9x

Angus brought 19 books and he gets $10 discount.

⇒ He paid for book is $19x - 10

But also Angus spent $7.5 more than Alana and Petra

⇒ 19x - 10 = 9x + 7.5

⇒ 10x = 17.5

⇒ x = 1.75

Thus the Cost of one book is $1.75.