The ratio of yellow to blue stamps that Pamela had was 5 : 2. The cost of each of the yellow stamps was $5 and the cost of each of the blue stamps was $10. Pamela sold 20% of the yellow stamps and the total cost of the unsold stamps was $400. How many yellow stamps did she have left?
| |
Yellow stamps |
Blue stamps |
| Before |
5 u |
2 u |
| Change |
- 1 u |
|
| After |
4 u |
2 u |
Number of yellow stamps sold
= 20% x 5 u
=
20100 x 5 u
= 1 u
| |
Yellow stamps |
Blue stamps |
Total |
| Number |
4 u |
2 u |
|
| Value |
$5 |
$10 |
|
| Total value |
20 u |
20 u |
$400 |
Total cost of unsold stamps
= 20 u + 20 u
= 40 u
40 u = 400
1 u = 400 ÷ 40 = 10
Number of yellow stamps that Pamela had left
= 20 u
= 20 x 10
= 200
Answer(s): 200
