The ratio of blue to brown stamps that Shiyun had was 5 : 4. The cost of each of the blue stamps was $4 and the cost of each of the brown stamps was $7. Shiyun sold 40% of the blue stamps and the total cost of the unsold stamps was $200. How many brown stamps did she have left?
| |
Blue stamps |
Brown stamps |
| Before |
5 u |
4 u |
| Change |
- 2 u |
|
| After |
3 u |
4 u |
Number of blue stamps sold
= 40% x 5 u
=
40100 x 5 u
= 2 u
| |
Blue stamps |
Brown stamps |
Total |
| Number |
3 u |
4 u |
|
| Value |
$4 |
$7 |
|
| Total value |
12 u |
28 u |
$200 |
Total cost of unsold stamps
= 12 u + 28 u
= 40 u
40 u = 200
1 u = 200 ÷ 40 = 5
Number of brown stamps that Shiyun had left
= 28 u
= 28 x 5
= 140
Answer(s): 140
