At a bookstore, Aubrey paid $15 for 1 textbook and 3 guide books. The textbook cost $6 more than the total cost of all the guide books.
- How much did 1 textbook cost?
- How much did 1 guide book cost?
(a)
Cost of 3 guide books = 1 u
Cost of 1 textbook = 1 u + 6
Total cost of 3 guide books and 1 textbook
= 1 u + 1 u + 6
= 2 u + 6
2 u + 6 = 15
2 u = 15 - 6
2 u = 9
1 u = 9 ÷ 2 = 4.50
Cost of 1 textbook
= 1 u + 6
= 4.50 + 6
= $10.50
(b)
Cost of 3 guide books = $4.50
Cost of 1 guide book
= 4.50 ÷ 3
= $1.50
Answer(s): (a) $10.50; (b) $1.50