Mary bought some Biology books at $7 each. She also bought an equal number of History books at a different price. The average price of one Biology and one History book was $5. Mary paid $44 less for the History books than the Biology books.
- What was the cost of one History book?
- How many Biology books did Mary buy?
|
Biology |
History |
Less |
Number |
1 u |
1 u |
|
Value |
$7 |
$3 |
|
Total value |
7 u |
3 u |
$44 |
(a)
Price of one History book
= 2 x 5 - 7
= 10 - 7
= $3
Amount that Mary paid less for History books than Biology books
= 7 u - 3 u
= 4 u
4 u = 44
1 u = 44 ÷ 4 = 11
Number of Biology books that Mary bought
= 1 u
= 11
Answer(s): (a) $3; (b) 11