The ratio of white to green stamps that Penelope had was 5 : 3. The cost of each of the white stamps was $2 and the cost of each of the green stamps was $7. Penelope sold 20% of the white stamps and the total cost of the unsold stamps was $203. How many green stamps did she have left?
| |
White stamps |
Green stamps |
| Before |
5 u |
3 u |
| Change |
- 1 u |
|
| After |
4 u |
3 u |
Number of white stamps sold
= 20% x 5 u
=
20100 x 5 u
= 1 u
| |
White stamps |
Green stamps |
Total |
| Number |
4 u |
3 u |
|
| Value |
$2 |
$7 |
|
| Total value |
8 u |
21 u |
$203 |
Total cost of unsold stamps
= 8 u + 21 u
= 29 u
29 u = 203
1 u = 203 ÷ 29 = 7
Number of green stamps that Penelope had left
= 21 u
= 21 x 7
= 147
Answer(s): 147
