The ratio of red to white stamps that Elyse had was 5 : 2. The cost of each of the red stamps was $3 and the cost of each of the white stamps was $4. Elyse sold 40% of the red stamps and the total cost of the unsold stamps was $68. How many red stamps did she have left?
| |
Red stamps |
White stamps |
| Before |
5 u |
2 u |
| Change |
- 2 u |
|
| After |
3 u |
2 u |
Number of red stamps sold
= 40% x 5 u
=
40100 x 5 u
= 2 u
| |
Red stamps |
White stamps |
Total |
| Number |
3 u |
2 u |
|
| Value |
$3 |
$4 |
|
| Total value |
9 u |
8 u |
$68 |
Total cost of unsold stamps
= 9 u + 8 u
= 17 u
17 u = 68
1 u = 68 ÷ 17 = 4
Number of red stamps that Elyse had left
= 9 u
= 9 x 4
= 36
Answer(s): 36
