The ratio of the number of red coins to green coins is 3 : 1. After Archie gives away 60 red coins and buys another 70 green coins, there is equal number of red coins and green coins. How many coins does Archie have now?
| |
Red |
Green |
| Before |
3 u |
1 u |
| Change |
- 60 |
+ 70 |
| After |
3 u - 60 |
1 u + 70 |
The number of red coins and green coins in the end is the same.
3 u - 60 = 1 u + 70
3 u - 1 u = 70 + 60
2 u = 130
1 u = 130 ÷ 2 = 65
Number of coins that Archie has now
= 3 u - 60 + 1 u + 70
= 3 u + 1 u - 60 + 70
= 4 u + 10
= 4 x 65 + 10
= 260 + 10
= 270
Answer(s): 270
