Min has a bag containing some orange and black cards. If she removes 4 orange cards, 40% of the cards in the bag are black. If she removes another 25 black cards, 20% of the cards in the bag are black. How many orange cards are in the bag?
| |
Orange cards |
Black cards |
| Before |
12 u + 4 |
8 u |
| Change 1 |
- 4 |
|
| After 1 |
3x4 =
12 u |
2x4 =
8 u |
| Change 2 |
|
- 25 |
| After 2 |
4x3 =
12 u |
1x3 =
3 u |
40% =
40100 =
2520% =
20100 =
15The number of orange cards remains unchanged at the second change when she removes another 25 black cards. Make the number of orange cards the same at the second change. LCM of 3 and 4 is 12.
Number of black cards removed
= 8 u - 3 u
= 5 u
5 u = 25
1 u = 25 ÷ 5 = 5
Number of orange cards at first
= 12 u + 4
= 12 x 5 + 4
= 60 + 4
= 64
Answer(s): 64
