The ratio of brown to grey stamps that Xylia had was 5 : 3. The cost of each of the brown stamps was $5 and the cost of each of the grey stamps was $10. Xylia sold 60% of the brown stamps and the total cost of the unsold stamps was $400. How many grey stamps did she have left?
| |
Brown stamps |
Grey stamps |
| Before |
5 u |
3 u |
| Change |
- 3 u |
|
| After |
2 u |
3 u |
Number of brown stamps sold
= 60% x 5 u
=
60100 x 5 u
= 3 u
| |
Brown stamps |
Grey stamps |
Total |
| Number |
2 u |
3 u |
|
| Value |
$5 |
$10 |
|
| Total value |
10 u |
30 u |
$400 |
Total cost of unsold stamps
= 10 u + 30 u
= 40 u
40 u = 400
1 u = 400 ÷ 40 = 10
Number of grey stamps that Xylia had left
= 30 u
= 30 x 10
= 300
Answer(s): 300
