The ratio of red to blue stamps that Opal had was 5 : 4. The cost of each of the red stamps was $3 and the cost of each of the blue stamps was $6. Opal sold 60% of the red stamps and the total cost of the unsold stamps was $120. How many blue stamps did she have left?
|
Red stamps |
Blue stamps |
Before |
5 u |
4 u |
Change |
- 3 u |
|
After |
2 u |
4 u |
Number of red stamps sold
= 60% x 5 u
=
60100 x 5 u
= 3 u
|
Red stamps |
Blue stamps |
Total |
Number |
2 u |
4 u |
|
Value |
$3 |
$6 |
|
Total value |
6 u |
24 u |
$120 |
Total cost of unsold stamps
= 6 u + 24 u
= 30 u
30 u = 120
1 u = 120 ÷ 30 = 4
Number of blue stamps that Opal had left
= 24 u
= 24 x 4
= 96
Answer(s): 96