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