Answer: £27.96
Explanation:
Since the bookshop has an offer. "Buy one book and get one free!" and we are told that Ria gets 8 books from the shop with that offer. This simply means that Ria bought 4 books and also got 4 free.
Since the normal price of each book is £6.99 and Ria bought 4 books, the amount Ria spend will be:
=£6.99 × 4
= £27.96