Min has a bag containing some black and yellow stickers. If she removes 10 black stickers, 30% of the stickers in the bag are yellow. If she removes another 50 yellow stickers, 20% of the stickers in the bag are yellow. How many black stickers are in the bag?
| |
Black stickers |
Yellow stickers |
| Before |
28 u + 10 |
12 u |
| Change 1 |
- 10 |
|
| After 1 |
7x4 =
28 u |
3x4 =
12 u |
| Change 2 |
|
- 50 |
| After 2 |
4x7 =
28 u |
1x7 =
7 u |
30% =
30100 =
31020% =
20100 =
15The number of black stickers remains unchanged at the second change when she removes another 50 yellow stickers. Make the number of black stickers the same at the second change. LCM of 7 and 4 is 28.
Number of yellow stickers removed
= 12 u - 7 u
= 5 u
5 u = 50
1 u = 50 ÷ 5 = 10
Number of black stickers at first
= 28 u + 10
= 28 x 10 + 10
= 280 + 10
= 290
Answer(s): 290
