The ratio of yellow to white stamps that Tammy had was 5 : 2. The cost of each of the yellow stamps was $1 and the cost of each of the white stamps was $5. Tammy sold 20% of the yellow stamps and the total cost of the unsold stamps was $56. How many yellow stamps did she have left?
| |
Yellow stamps |
White stamps |
| Before |
5 u |
2 u |
| Change |
- 1 u |
|
| After |
4 u |
2 u |
Number of yellow stamps sold
= 20% x 5 u
=
20100 x 5 u
= 1 u
| |
Yellow stamps |
White stamps |
Total |
| Number |
4 u |
2 u |
|
| Value |
$1 |
$5 |
|
| Total value |
4 u |
10 u |
$56 |
Total cost of unsold stamps
= 4 u + 10 u
= 14 u
14 u = 56
1 u = 56 ÷ 14 = 4
Number of yellow stamps that Tammy had left
= 4 u
= 4 x 4
= 16
Answer(s): 16
