The ratio of black to green stamps that Gabby had was 5 : 3. The cost of each of the black stamps was $1 and the cost of each of the green stamps was $5. Gabby sold 20% of the black stamps and the total cost of the unsold stamps was $228. How many green stamps did she have left?
|
Black stamps |
Green stamps |
Before |
5 u |
3 u |
Change |
- 1 u |
|
After |
4 u |
3 u |
Number of black stamps sold
= 20% x 5 u
=
20100 x 5 u
= 1 u
|
Black stamps |
Green stamps |
Total |
Number |
4 u |
3 u |
|
Value |
$1 |
$5 |
|
Total value |
4 u |
15 u |
$228 |
Total cost of unsold stamps
= 4 u + 15 u
= 19 u
19 u = 228
1 u = 228 ÷ 19 = 12
Number of green stamps that Gabby had left
= 15 u
= 15 x 12
= 180
Answer(s): 180