Barbara bought some Chemistry books at $13 each. She also bought an equal number of History books at a different price. The average price of one Chemistry and one History book was $8. Barbara paid $20 more for the Chemistry books than the History books.
- What was the cost of one History book?
- How many Chemistry books did Barbara buy?
|
Chemistry |
History |
More |
Number |
1 u |
1 u |
|
Value |
$13 |
$3 |
|
Total value |
13 u |
3 u |
$20 |
(a)
Price of one History book
= 2 x 8 - 13
= 16 - 13
= $3
Amount that Barbara paid more for Chemistry books than History books
= 13 u - 3 u
= 10 u
10 u = 20
1 u = 20 ÷ 10 = 2
Number of Chemistry books that Barbara bought
= 1 u
= 2
Answer(s): (a) $3; (b) 2