The ratio of grey to purple stamps that Cindy had was 5 : 4. The cost of each of the grey stamps was $1 and the cost of each of the purple stamps was $5. Cindy sold 20% of the grey stamps and the total cost of the unsold stamps was $192. How many purple stamps did she have left?
| |
Grey stamps |
Purple stamps |
| Before |
5 u |
4 u |
| Change |
- 1 u |
|
| After |
4 u |
4 u |
Number of grey stamps sold
= 20% x 5 u
=
20100 x 5 u
= 1 u
| |
Grey stamps |
Purple stamps |
Total |
| Number |
4 u |
4 u |
|
| Value |
$1 |
$5 |
|
| Total value |
4 u |
20 u |
$192 |
Total cost of unsold stamps
= 4 u + 20 u
= 24 u
24 u = 192
1 u = 192 ÷ 24 = 8
Number of purple stamps that Cindy had left
= 20 u
= 20 x 8
= 160
Answer(s): 160
