The ratio of blue to green stamps that Esther had was 4 : 3. The cost of each of the blue stamps was $4 and the cost of each of the green stamps was $7. Esther sold 25% of the blue stamps and the total cost of the unsold stamps was $396. How many blue stamps did she have left?
| |
Blue stamps |
Green stamps |
| Before |
4 u |
3 u |
| Change |
- 1 u |
|
| After |
3 u |
3 u |
Number of blue stamps sold
= 25% x 4 u
=
25100 x 4 u
= 1 u
| |
Blue stamps |
Green stamps |
Total |
| Number |
3 u |
3 u |
|
| Value |
$4 |
$7 |
|
| Total value |
12 u |
21 u |
$396 |
Total cost of unsold stamps
= 12 u + 21 u
= 33 u
33 u = 396
1 u = 396 ÷ 33 = 12
Number of blue stamps that Esther had left
= 12 u
= 12 x 12
= 144
Answer(s): 144
