The ratio of the number of red marbles to green marbles is 9 : 4. After Tim gives away 10 red marbles and buys another 40 green marbles, there is equal number of red marbles and green marbles. How many marbles does Tim have now?
| |
Red |
Green |
| Before |
9 u |
4 u |
| Change |
- 10 |
+ 40 |
| After |
9 u - 10 |
4 u + 40 |
The number of red marbles and green marbles in the end is the same.
9 u - 10 = 4 u + 40
9 u - 4 u = 40 + 10
5 u = 50
1 u = 50 ÷ 5 = 10
Number of marbles that Tim has now
= 9 u - 10 + 4 u + 40
= 9 u + 4 u - 10 + 40
= 13 u + 30
= 13 x 10 + 30
= 130 + 30
= 160
Answer(s): 160
