The ratio of gold to silver stamps that Gwen had was 5 : 3. The cost of each of the gold stamps was $1 and the cost of each of the silver stamps was $6. Gwen sold 40% of the gold stamps and the total cost of the unsold stamps was $42. How many gold stamps did she have left?
| |
Gold stamps |
Silver 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 |
Silver stamps |
Total |
| Number |
3 u |
3 u |
|
| Value |
$1 |
$6 |
|
| Total value |
3 u |
18 u |
$42 |
Total cost of unsold stamps
= 3 u + 18 u
= 21 u
21 u = 42
1 u = 42 ÷ 21 = 2
Number of gold stamps that Gwen had left
= 3 u
= 3 x 2
= 6
Answer(s): 6
