The ratio of gold to grey stamps that Gwen had was 5 : 2. The cost of each of the gold stamps was $3 and the cost of each of the grey stamps was $4. Gwen sold 40% of the gold stamps and the total cost of the unsold stamps was $34. How many grey stamps did she have left?
| |
Gold stamps |
Grey stamps |
| Before |
5 u |
2 u |
| Change |
- 2 u |
|
| After |
3 u |
2 u |
Number of gold stamps sold
= 40% x 5 u
=
40100 x 5 u
= 2 u
| |
Gold stamps |
Grey stamps |
Total |
| Number |
3 u |
2 u |
|
| Value |
$3 |
$4 |
|
| Total value |
9 u |
8 u |
$34 |
Total cost of unsold stamps
= 9 u + 8 u
= 17 u
17 u = 34
1 u = 34 ÷ 17 = 2
Number of grey stamps that Gwen had left
= 8 u
= 8 x 2
= 16
Answer(s): 16
