Gabby has a bag containing some green and black marbles. If she removes 4 green marbles, 40% of the marbles in the bag are black. If she removes another 60 black marbles, 10% of the marbles in the bag are black. How many green marbles are in the bag?
| |
Green marbles |
Black marbles |
| Before |
9 u + 4 |
6 u |
| Change 1 |
- 4 |
|
| After 1 |
3x3 =
9 u |
2x3 =
6 u |
| Change 2 |
|
- 60 |
| After 2 |
9x1 =
9 u |
1x1 =
1 u |
40% =
40100 =
2510% =
10100 =
110The number of green marbles remains unchanged at the second change when she removes another 60 black marbles. Make the number of green marbles the same at the second change. LCM of 3 and 9 is 9.
Number of black marbles removed
= 6 u - 1 u
= 5 u
5 u = 60
1 u = 60 ÷ 5 = 12
Number of green marbles at first
= 9 u + 4
= 9 x 12 + 4
= 108 + 4
= 112
Answer(s): 112
