The ratio of the number of red marbles to green marbles is 8 : 3. After Carl gives away 10 red marbles and buys another 50 green marbles, there is equal number of red marbles and green marbles. How many marbles does Carl have now?
| |
Red |
Green |
| Before |
8 u |
3 u |
| Change |
- 10 |
+ 50 |
| After |
8 u - 10 |
3 u + 50 |
The number of red marbles and green marbles in the end is the same.
8 u - 10 = 3 u + 50
8 u - 3 u = 50 + 10
5 u = 60
1 u = 60 ÷ 5 = 12
Number of marbles that Carl has now
= 8 u - 10 + 3 u + 50
= 8 u + 3 u - 10 + 50
= 11 u + 40
= 11 x 12 + 40
= 132 + 40
= 172
Answer(s): 172
