The ratio of gold to green stamps that Emma had was 5 : 3. The cost of each of the gold stamps was $1 and the cost of each of the green stamps was $4. Emma sold 40% of the gold stamps and the total cost of the unsold stamps was $150. How many green stamps did she have left?
| |
Gold stamps |
Green stamps |
| Before |
5 u |
3 u |
| Change |
- 2 u |
|
| After |
3 u |
3 u |
Number of gold stamps sold
= 40% x 5 u
=
40100 x 5 u
= 2 u
| |
Gold stamps |
Green stamps |
Total |
| Number |
3 u |
3 u |
|
| Value |
$1 |
$4 |
|
| Total value |
3 u |
12 u |
$150 |
Total cost of unsold stamps
= 3 u + 12 u
= 15 u
15 u = 150
1 u = 150 ÷ 15 = 10
Number of green stamps that Emma had left
= 12 u
= 12 x 10
= 120
Answer(s): 120
