Answer :
Alana and Petra bought 9 books combined.
Angus bought 19 books and had a $10 discount.
Angus spent $5 more than Alana and Petra combined.
This means that the price of 19 books is $15 more than the price of 9 books. 19 books is 10 books more than 9 books.
Giving you 10 books = $15, 1 book = $1.50
Angus bought 19 books and had a $10 discount.
Angus spent $5 more than Alana and Petra combined.
This means that the price of 19 books is $15 more than the price of 9 books. 19 books is 10 books more than 9 books.
Giving you 10 books = $15, 1 book = $1.50