The ratio of blue to silver stamps that Yoko had was 5 : 4. The cost of each of the blue stamps was $2 and the cost of each of the silver stamps was $4. Yoko sold 60% of the blue stamps and the total cost of the unsold stamps was $240. How many silver stamps did she have left?
| |
Blue stamps |
Silver stamps |
| Before |
5 u |
4 u |
| Change |
- 3 u |
|
| After |
2 u |
4 u |
Number of blue stamps sold
= 60% x 5 u
=
60100 x 5 u
= 3 u
| |
Blue stamps |
Silver stamps |
Total |
| Number |
2 u |
4 u |
|
| Value |
$2 |
$4 |
|
| Total value |
4 u |
16 u |
$240 |
Total cost of unsold stamps
= 4 u + 16 u
= 20 u
20 u = 240
1 u = 240 ÷ 20 = 12
Number of silver stamps that Yoko had left
= 16 u
= 16 x 12
= 192
Answer(s): 192
