The ratio of the number of green coins to red coins is 9 : 7. After Dylan gives away 30 green coins and buys another 80 red coins, there is equal number of green coins and red coins. How many coins does Dylan have now?
| |
Green |
Red |
| Before |
9 u |
7 u |
| Change |
- 30 |
+ 80 |
| After |
9 u - 30 |
7 u + 80 |
The number of green coins and red coins in the end is the same.
9 u - 30 = 7 u + 80
9 u - 7 u = 80 + 30
2 u = 110
1 u = 110 ÷ 2 = 55
Number of coins that Dylan has now
= 9 u - 30 + 7 u + 80
= 9 u + 7 u - 30 + 80
= 16 u + 50
= 16 x 55 + 50
= 880 + 50
= 930
Answer(s): 930
