The ratio of purple to blue stamps that Shannon had was 5 : 3. The cost of each of the purple stamps was $4 and the cost of each of the blue stamps was $5. Shannon sold 20% of the purple stamps and the total cost of the unsold stamps was $124. How many blue stamps did she have left?
| |
Purple stamps |
Blue stamps |
| Before |
5 u |
3 u |
| Change |
- 1 u |
|
| After |
4 u |
3 u |
Number of purple stamps sold
= 20% x 5 u
=
20100 x 5 u
= 1 u
| |
Purple stamps |
Blue stamps |
Total |
| Number |
4 u |
3 u |
|
| Value |
$4 |
$5 |
|
| Total value |
16 u |
15 u |
$124 |
Total cost of unsold stamps
= 16 u + 15 u
= 31 u
31 u = 124
1 u = 124 ÷ 31 = 4
Number of blue stamps that Shannon had left
= 15 u
= 15 x 4
= 60
Answer(s): 60
