The ratio of the number of red marbles to blue marbles is 8 : 5. After Ethan gives away 10 red marbles and buys another 50 blue marbles, there is equal number of red marbles and blue marbles. How many marbles does Ethan have now?
| |
Red |
Blue |
| Before |
8 u |
5 u |
| Change |
- 10 |
+ 50 |
| After |
8 u - 10 |
5 u + 50 |
The number of red marbles and blue marbles in the end is the same.
8 u - 10 = 5 u + 50
8 u - 5 u = 50 + 10
3 u = 60
1 u = 60 ÷ 3 = 20
Number of marbles that Ethan has now
= 8 u - 10 + 5 u + 50
= 8 u + 5 u - 10 + 50
= 13 u + 40
= 13 x 20 + 40
= 260 + 40
= 300
Answer(s): 300
