The ratio of purple to grey stamps that Hilda had was 5 : 3. The cost of each of the purple stamps was $5 and the cost of each of the grey stamps was $8. Hilda sold 40% of the purple stamps and the total cost of the unsold stamps was $78. How many purple stamps did she have left?
| |
Purple stamps |
Grey stamps |
| Before |
5 u |
3 u |
| Change |
- 2 u |
|
| After |
3 u |
3 u |
Number of purple stamps sold
= 40% x 5 u
=
40100 x 5 u
= 2 u
| |
Purple stamps |
Grey stamps |
Total |
| Number |
3 u |
3 u |
|
| Value |
$5 |
$8 |
|
| Total value |
15 u |
24 u |
$78 |
Total cost of unsold stamps
= 15 u + 24 u
= 39 u
39 u = 78
1 u = 78 ÷ 39 = 2
Number of purple stamps that Hilda had left
= 15 u
= 15 x 2
= 30
Answer(s): 30
