The ratio of the number of red coins to blue coins is 8 : 3. After Charlie gives away 20 red coins and buys another 70 blue coins, there is equal number of red coins and blue coins. How many coins does Charlie have now?
|
Red |
Blue |
Before |
8 u |
3 u |
Change |
- 20 |
+ 70 |
After |
8 u - 20 |
3 u + 70 |
The number of red coins and blue coins in the end is the same.
8 u - 20 = 3 u + 70
8 u - 3 u = 70 + 20
5 u = 90
1 u = 90 ÷ 5 = 18
Number of coins that Charlie has now
= 8 u - 20 + 3 u + 70
= 8 u + 3 u - 20 + 70
= 11 u + 50
= 11 x 18 + 50
= 198 + 50
= 248
Answer(s): 248