Barbara bought some History books at $13 each. She also bought an equal number of Social Science books at a different price. The average price of one History and one Social Science book was $11. Barbara paid $24 less for the Social Science books than the History books.
- What was the cost of one Social Science book?
- How many History books did Barbara buy?
|
History |
Social Science |
Less |
Number |
1 u |
1 u |
|
Value |
$13 |
$9 |
|
Total value |
13 u |
9 u |
$24 |
(a)
Price of one Social Science book
= 2 x 11 - 13
= 22 - 13
= $9
Amount that Barbara paid less for Social Science books than History books
= 13 u - 9 u
= 4 u
4 u = 24
1 u = 24 ÷ 4 = 6
Number of History books that Barbara bought
= 1 u
= 6
Answer(s): (a) $9; (b) 6