Anna bought some Maths books at $15 each. She also bought an equal number of Chemistry books at a different price. The average price of one Maths and one Chemistry book was $12. Anna paid $24 more for the Maths books than the Chemistry books.
- What was the cost of one Chemistry book?
- How many Maths books did Anna buy?
|
Maths |
Chemistry |
More |
Number |
1 u |
1 u |
|
Value |
$15 |
$9 |
|
Total value |
15 u |
9 u |
$24 |
(a)
Price of one Chemistry book
= 2 x 12 - 15
= 24 - 15
= $9
Amount that Anna paid more for Maths books than Chemistry books
= 15 u - 9 u
= 6 u
6 u = 24
1 u = 24 ÷ 6 = 4
Number of Maths books that Anna bought
= 1 u
= 4
Answer(s): (a) $9; (b) 4