The ratio of black to green stamps that Esther had was 5 : 3. The cost of each of the black stamps was $2 and the cost of each of the green stamps was $6. Esther sold 40% of the black stamps and the total cost of the unsold stamps was $96. How many black stamps did she have left?
| |
Black stamps |
Green stamps |
| Before |
5 u |
3 u |
| Change |
- 2 u |
|
| After |
3 u |
3 u |
Number of black stamps sold
= 40% x 5 u
=
40100 x 5 u
= 2 u
| |
Black stamps |
Green stamps |
Total |
| Number |
3 u |
3 u |
|
| Value |
$2 |
$6 |
|
| Total value |
6 u |
18 u |
$96 |
Total cost of unsold stamps
= 6 u + 18 u
= 24 u
24 u = 96
1 u = 96 ÷ 24 = 4
Number of black stamps that Esther had left
= 6 u
= 6 x 4
= 24
Answer(s): 24
