The ratio of grey to red stamps that Zoe had was 5 : 2. The cost of each of the grey stamps was $2 and the cost of each of the red stamps was $6. Zoe sold 60% of the grey stamps and the total cost of the unsold stamps was $128. How many grey stamps did she have left?
| |
Grey stamps |
Red stamps |
| Before |
5 u |
2 u |
| Change |
- 3 u |
|
| After |
2 u |
2 u |
Number of grey stamps sold
= 60% x 5 u
=
60100 x 5 u
= 3 u
| |
Grey stamps |
Red stamps |
Total |
| Number |
2 u |
2 u |
|
| Value |
$2 |
$6 |
|
| Total value |
4 u |
12 u |
$128 |
Total cost of unsold stamps
= 4 u + 12 u
= 16 u
16 u = 128
1 u = 128 ÷ 16 = 8
Number of grey stamps that Zoe had left
= 4 u
= 4 x 8
= 32
Answer(s): 32
