Fanny has a bag containing some yellow and silver stamps. If she removes 15 yellow stamps, 20% of the stamps in the bag are silver. If she removes another 15 silver stamps, 10% of the stamps in the bag are silver. How many yellow stamps are in the bag?
| |
Yellow stamps |
Silver stamps |
| Before |
36 u + 15 |
9 u |
| Change 1 |
- 15 |
|
| After 1 |
4x9 =
36 u |
1x9 =
9 u |
| Change 2 |
|
- 15 |
| After 2 |
9x4 =
36 u |
1x4 =
4 u |
20% =
20100 =
1510% =
10100 =
110The number of yellow stamps remains unchanged at the second change when she removes another 15 silver stamps. Make the number of yellow stamps the same at the second change. LCM of 4 and 9 is 36.
Number of silver stamps removed
= 9 u - 4 u
= 5 u
5 u = 15
1 u = 15 ÷ 5 = 3
Number of yellow stamps at first
= 36 u + 15
= 36 x 3 + 15
= 108 + 15
= 123
Answer(s): 123
