The ratio of silver to yellow stamps that Penelope had was 5 : 4. The cost of each of the silver stamps was $4 and the cost of each of the yellow stamps was $5. Penelope sold 60% of the silver stamps and the total cost of the unsold stamps was $168. How many yellow stamps did she have left?
| |
Silver stamps |
Yellow stamps |
| Before |
5 u |
4 u |
| Change |
- 3 u |
|
| After |
2 u |
4 u |
Number of silver stamps sold
= 60% x 5 u
=
60100 x 5 u
= 3 u
| |
Silver stamps |
Yellow stamps |
Total |
| Number |
2 u |
4 u |
|
| Value |
$4 |
$5 |
|
| Total value |
8 u |
20 u |
$168 |
Total cost of unsold stamps
= 8 u + 20 u
= 28 u
28 u = 168
1 u = 168 ÷ 28 = 6
Number of yellow stamps that Penelope had left
= 20 u
= 20 x 6
= 120
Answer(s): 120
