The ratio of the number of blue coins to red coins is 9 : 4. After Riordan gives away 30 blue coins and buys another 60 red coins, there is equal number of blue coins and red coins. How many coins does Riordan have now?
| |
Blue |
Red |
| Before |
9 u |
4 u |
| Change |
- 30 |
+ 60 |
| After |
9 u - 30 |
4 u + 60 |
The number of blue coins and red coins in the end is the same.
9 u - 30 = 4 u + 60
9 u - 4 u = 60 + 30
5 u = 90
1 u = 90 ÷ 5 = 18
Number of coins that Riordan has now
= 9 u - 30 + 4 u + 60
= 9 u + 4 u - 30 + 60
= 13 u + 30
= 13 x 18 + 30
= 234 + 30
= 264
Answer(s): 264
