Kimberly has a bag containing some green and black erasers. If she adds in 19 green erasers, 25% of the erasers in the bag are black. If she adds in another 4 black erasers, 50% of the erasers in the bag are black. How many green erasers are in the bag?
| |
Green erasers |
Black erasers |
| Before |
3 u - 19 |
1 u |
| Change 1 |
+ 19 |
|
| After 1 |
3x1 =
3 u |
1x1 =
1 u |
| Change 2 |
|
+ 4 |
| After 2 |
1x3 =
3 u |
1x3 =
3 u |
25% =
25100 =
1450% =
50100 =
12The number of green erasers remains unchanged at the second change when she adds in another 4 black erasers. Make the number of green erasers the same at the second change. LCM of 3 and 1 is 3.
Number of black erasers added
= 3 u - 1 u
= 2 u
2 u = 4
1 u = 4 ÷ 2 = 2
Number of green erasers at first
= 3 u - 19
= 3 x 2 - 19
= 6 - 19
= -13
Answer(s): -13
