The ratio of green to red stamps that Gwen had was 5 : 4. The cost of each of the green stamps was $3 and the cost of each of the red stamps was $7. Gwen sold 60% of the green stamps and the total cost of the unsold stamps was $408. How many red stamps did she have left?
| |
Green stamps |
Red stamps |
| Before |
5 u |
4 u |
| Change |
- 3 u |
|
| After |
2 u |
4 u |
Number of green stamps sold
= 60% x 5 u
=
60100 x 5 u
= 3 u
| |
Green stamps |
Red stamps |
Total |
| Number |
2 u |
4 u |
|
| Value |
$3 |
$7 |
|
| Total value |
6 u |
28 u |
$408 |
Total cost of unsold stamps
= 6 u + 28 u
= 34 u
34 u = 408
1 u = 408 ÷ 34 = 12
Number of red stamps that Gwen had left
= 28 u
= 28 x 12
= 336
Answer(s): 336
