The ratio of the number of green cards to blue cards is 3 : 1. After Paul gives away 30 green cards and buys another 80 blue cards, there is equal number of green cards and blue cards. How many cards does Paul have now?
| |
Green |
Blue |
| Before |
3 u |
1 u |
| Change |
- 30 |
+ 80 |
| After |
3 u - 30 |
1 u + 80 |
The number of green cards and blue cards in the end is the same.
3 u - 30 = 1 u + 80
3 u - 1 u = 80 + 30
2 u = 110
1 u = 110 ÷ 2 = 55
Number of cards that Paul has now
= 3 u - 30 + 1 u + 80
= 3 u + 1 u - 30 + 80
= 4 u + 50
= 4 x 55 + 50
= 220 + 50
= 270
Answer(s): 270
