The ratio of grey to red stamps that Lynn had was 4 : 3. The cost of each of the grey stamps was $4 and the cost of each of the red stamps was $9. Lynn sold 50% of the grey stamps and the total cost of the unsold stamps was $315. How many red stamps did she have left?
| |
Grey stamps |
Red stamps |
| Before |
4 u |
3 u |
| Change |
- 2 u |
|
| After |
2 u |
3 u |
Number of grey stamps sold
= 50% x 4 u
=
50100 x 4 u
= 2 u
| |
Grey stamps |
Red stamps |
Total |
| Number |
2 u |
3 u |
|
| Value |
$4 |
$9 |
|
| Total value |
8 u |
27 u |
$315 |
Total cost of unsold stamps
= 8 u + 27 u
= 35 u
35 u = 315
1 u = 315 ÷ 35 = 9
Number of red stamps that Lynn had left
= 27 u
= 27 x 9
= 243
Answer(s): 243
