The ratio of blue to red stamps that Hilda had was 5 : 2. The cost of each of the blue stamps was $1 and the cost of each of the red stamps was $2. Hilda sold 40% of the blue stamps and the total cost of the unsold stamps was $28. How many red stamps did she have left?
| |
Blue stamps |
Red stamps |
| Before |
5 u |
2 u |
| Change |
- 2 u |
|
| After |
3 u |
2 u |
Number of blue stamps sold
= 40% x 5 u
=
40100 x 5 u
= 2 u
| |
Blue stamps |
Red stamps |
Total |
| Number |
3 u |
2 u |
|
| Value |
$1 |
$2 |
|
| Total value |
3 u |
4 u |
$28 |
Total cost of unsold stamps
= 3 u + 4 u
= 7 u
7 u = 28
1 u = 28 ÷ 7 = 4
Number of red stamps that Hilda had left
= 4 u
= 4 x 4
= 16
Answer(s): 16
