The ratio of blue to yellow stamps that Fanny had was 5 : 2. The cost of each of the blue stamps was $1 and the cost of each of the yellow stamps was $5. Fanny sold 60% of the blue stamps and the total cost of the unsold stamps was $36. How many yellow stamps did she have left?
| |
Blue stamps |
Yellow stamps |
| Before |
5 u |
2 u |
| Change |
- 3 u |
|
| After |
2 u |
2 u |
Number of blue stamps sold
= 60% x 5 u
=
60100 x 5 u
= 3 u
| |
Blue stamps |
Yellow stamps |
Total |
| Number |
2 u |
2 u |
|
| Value |
$1 |
$5 |
|
| Total value |
2 u |
10 u |
$36 |
Total cost of unsold stamps
= 2 u + 10 u
= 12 u
12 u = 36
1 u = 36 ÷ 12 = 3
Number of yellow stamps that Fanny had left
= 10 u
= 10 x 3
= 30
Answer(s): 30
