The ratio of the number of blue coins to red coins is 3 : 1. After Vincent gives away 40 blue coins and buys another 90 red coins, there is equal number of blue coins and red coins. How many coins does Vincent have now?
| |
Blue |
Red |
| Before |
3 u |
1 u |
| Change |
- 40 |
+ 90 |
| After |
3 u - 40 |
1 u + 90 |
The number of blue coins and red coins in the end is the same.
3 u - 40 = 1 u + 90
3 u - 1 u = 90 + 40
2 u = 130
1 u = 130 ÷ 2 = 65
Number of coins that Vincent has now
= 3 u - 40 + 1 u + 90
= 3 u + 1 u - 40 + 90
= 4 u + 50
= 4 x 65 + 50
= 260 + 50
= 310
Answer(s): 310
