The ratio of yellow to pink stamps that Linda had was 5 : 2. The cost of each of the yellow stamps was $2 and the cost of each of the pink stamps was $7. Linda sold 60% of the yellow stamps and the total cost of the unsold stamps was $90. How many yellow stamps did she have left?
|
Yellow stamps |
Pink stamps |
Before |
5 u |
2 u |
Change |
- 3 u |
|
After |
2 u |
2 u |
Number of yellow stamps sold
= 60% x 5 u
=
60100 x 5 u
= 3 u
|
Yellow stamps |
Pink stamps |
Total |
Number |
2 u |
2 u |
|
Value |
$2 |
$7 |
|
Total value |
4 u |
14 u |
$90 |
Total cost of unsold stamps
= 4 u + 14 u
= 18 u
18 u = 90
1 u = 90 ÷ 18 = 5
Number of yellow stamps that Linda had left
= 4 u
= 4 x 5
= 20
Answer(s): 20