The ratio of black to white stamps that Kathy had was 5 : 4. The cost of each of the black stamps was $2 and the cost of each of the white stamps was $6. Kathy sold 60% of the black stamps and the total cost of the unsold stamps was $308. How many white stamps did she have left?
| |
Black stamps |
White stamps |
| Before |
5 u |
4 u |
| Change |
- 3 u |
|
| After |
2 u |
4 u |
Number of black stamps sold
= 60% x 5 u
=
60100 x 5 u
= 3 u
| |
Black stamps |
White stamps |
Total |
| Number |
2 u |
4 u |
|
| Value |
$2 |
$6 |
|
| Total value |
4 u |
24 u |
$308 |
Total cost of unsold stamps
= 4 u + 24 u
= 28 u
28 u = 308
1 u = 308 ÷ 28 = 11
Number of white stamps that Kathy had left
= 24 u
= 24 x 11
= 264
Answer(s): 264
