The ratio of brown to grey stamps that Min had was 4 : 3. The cost of each of the brown stamps was $1 and the cost of each of the grey stamps was $3. Min sold 25% of the brown stamps and the total cost of the unsold stamps was $84. How many brown stamps did she have left?
| |
Brown stamps |
Grey stamps |
| Before |
4 u |
3 u |
| Change |
- 1 u |
|
| After |
3 u |
3 u |
Number of brown stamps sold
= 25% x 4 u
=
25100 x 4 u
= 1 u
| |
Brown stamps |
Grey stamps |
Total |
| Number |
3 u |
3 u |
|
| Value |
$1 |
$3 |
|
| Total value |
3 u |
9 u |
$84 |
Total cost of unsold stamps
= 3 u + 9 u
= 12 u
12 u = 84
1 u = 84 ÷ 12 = 7
Number of brown stamps that Min had left
= 3 u
= 3 x 7
= 21
Answer(s): 21
