Betty has a bag containing some gold and green cards. If she removes 10 gold cards, 30% of the cards in the bag are green. If she adds another 45 green cards, 40% of the cards in the bag are green. How many gold cards are in the bag?
| |
Gold cards |
Green cards |
| Before |
21 u + 10 |
9 u |
| Change 1 |
- 10 |
|
| After 1 |
7x3 =
21 u |
3x3 =
9 u |
| Change 2 |
|
+ 45 |
| After 2 |
3x7 =
21 u |
2x7 =
14 u |
30% =
30100 =
31040% =
40100 =
25The number of gold cards remains unchanged at the second change when she adds another 45 green cards. Make the number of gold cards the same at the second change. LCM of 7 and 3 is 21.
Number of green cards added
= 14 u - 9 u
= 5 u
5 u = 45
1 u = 45 ÷ 5 = 9
Number of gold cards at first
= 21 u + 10
= 21 x 9 + 10
= 189 + 10
= 199
Answer(s): 199
