Shiyun has a bag containing some yellow and silver beads. If she removes 5 yellow beads, 20% of the beads in the bag are silver. If she adds another 45 silver beads, 30% of the beads in the bag are silver. How many yellow beads are in the bag?
| |
Yellow beads |
Silver beads |
| Before |
28 u + 5 |
7 u |
| Change 1 |
- 5 |
|
| After 1 |
4x7 =
28 u |
1x7 =
7 u |
| Change 2 |
|
+ 45 |
| After 2 |
7x4 =
28 u |
3x4 =
12 u |
20% =
20100 =
1530% =
30100 =
310The number of yellow beads remains unchanged at the second change when she adds another 45 silver beads. Make the number of yellow beads the same at the second change. LCM of 4 and 7 is 28.
Number of silver beads added
= 12 u - 7 u
= 5 u
5 u = 45
1 u = 45 ÷ 5 = 9
Number of yellow beads at first
= 28 u + 5
= 28 x 9 + 5
= 252 + 5
= 257
Answer(s): 257
