The ratio of green to grey stamps that Hilda had was 5 : 2. The cost of each of the green stamps was $2 and the cost of each of the grey stamps was $3. Hilda sold 40% of the green stamps and the total cost of the unsold stamps was $36. How many grey stamps did she have left?
| |
Green stamps |
Grey stamps |
| Before |
5 u |
2 u |
| Change |
- 2 u |
|
| After |
3 u |
2 u |
Number of green stamps sold
= 40% x 5 u
=
40100 x 5 u
= 2 u
| |
Green stamps |
Grey stamps |
Total |
| Number |
3 u |
2 u |
|
| Value |
$2 |
$3 |
|
| Total value |
6 u |
6 u |
$36 |
Total cost of unsold stamps
= 6 u + 6 u
= 12 u
12 u = 36
1 u = 36 ÷ 12 = 3
Number of grey stamps that Hilda had left
= 6 u
= 6 x 3
= 18
Answer(s): 18
