Betty has a bag containing some orange and yellow erasers. If she removes 7 orange erasers, 30% 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 orange erasers are in the bag?
| |
Orange erasers |
Yellow erasers |
| Before |
28 u + 7 |
12 u |
| Change 1 |
- 7 |
|
| After 1 |
7x4 =
28 u |
3x4 =
12 u |
| Change 2 |
|
- 10 |
| After 2 |
4x7 =
28 u |
1x7 =
7 u |
30% =
30100 =
31020% =
20100 =
15The number of orange erasers remains unchanged at the second change when she removes another 10 yellow erasers. Make the number of orange erasers the same at the second change. LCM of 7 and 4 is 28.
Number of yellow erasers removed
= 12 u - 7 u
= 5 u
5 u = 10
1 u = 10 ÷ 5 = 2
Number of orange erasers at first
= 28 u + 7
= 28 x 2 + 7
= 56 + 7
= 63
Answer(s): 63
