The ratio of blue to white stamps that Joelle had was 5 : 4. The cost of each of the blue stamps was $3 and the cost of each of the white stamps was $7. Joelle sold 40% of the blue stamps and the total cost of the unsold stamps was $333. How many blue stamps did she have left?
| |
Blue stamps |
White stamps |
| Before |
5 u |
4 u |
| Change |
- 2 u |
|
| After |
3 u |
4 u |
Number of blue stamps sold
= 40% x 5 u
=
40100 x 5 u
= 2 u
| |
Blue stamps |
White stamps |
Total |
| Number |
3 u |
4 u |
|
| Value |
$3 |
$7 |
|
| Total value |
9 u |
28 u |
$333 |
Total cost of unsold stamps
= 9 u + 28 u
= 37 u
37 u = 333
1 u = 333 ÷ 37 = 9
Number of blue stamps that Joelle had left
= 9 u
= 9 x 9
= 81
Answer(s): 81
