Min has a bag containing some red and yellow erasers. If she removes 4 red erasers, 40% of the erasers in the bag are yellow. If she removes another 10 yellow erasers, 20% of the erasers in the bag are yellow. How many red erasers are in the bag?
| |
Red erasers |
Yellow erasers |
| Before |
12 u + 4 |
8 u |
| Change 1 |
- 4 |
|
| After 1 |
3x4 =
12 u |
2x4 =
8 u |
| Change 2 |
|
- 10 |
| After 2 |
4x3 =
12 u |
1x3 =
3 u |
40% =
40100 =
2520% =
20100 =
15The number of red erasers remains unchanged at the second change when she removes another 10 yellow erasers. Make the number of red erasers the same at the second change. LCM of 3 and 4 is 12.
Number of yellow erasers removed
= 8 u - 3 u
= 5 u
5 u = 10
1 u = 10 ÷ 5 = 2
Number of red erasers at first
= 12 u + 4
= 12 x 2 + 4
= 24 + 4
= 28
Answer(s): 28
