Rachel has a bag containing some orange and silver pens. If she removes 15 orange pens, 20% of the pens in the bag are silver. If she removes another 15 silver pens, 10% of the pens in the bag are silver. How many orange pens are in the bag?
| |
Orange pens |
Silver pens |
| 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 orange pens remains unchanged at the second change when she removes another 15 silver pens. Make the number of orange pens the same at the second change. LCM of 4 and 9 is 36.
Number of silver pens removed
= 9 u - 4 u
= 5 u
5 u = 15
1 u = 15 ÷ 5 = 3
Number of orange pens at first
= 36 u + 15
= 36 x 3 + 15
= 108 + 15
= 123
Answer(s): 123
