Fiona has a bag containing some green and red cards. If she adds in 16 green cards, 10% of the cards in the bag are red. If she adds in another 200 red cards, 60% of the cards in the bag are red. How many green cards are in the bag?
| |
Green cards |
Red cards |
| Before |
18 u - 16 |
2 u |
| Change 1 |
+ 16 |
|
| After 1 |
9x2 =
18 u |
1x2 =
2 u |
| Change 2 |
|
+ 200 |
| After 2 |
2x9 =
18 u |
3x9 =
27 u |
10% =
10100 =
11060% =
60100 =
35The number of green cards remains unchanged at the second change when she adds in another 200 red cards. Make the number of green cards the same at the second change. LCM of 9 and 2 is 18.
Number of red cards added
= 27 u - 2 u
= 25 u
25 u = 200
1 u = 200 ÷ 25 = 8
Number of green cards at first
= 18 u - 16
= 18 x 8 - 16
= 144 - 16
= 128
Answer(s): 128
