The ratio of the number of blue beads to green beads is 3 : 1. After David gives away 10 blue beads and buys another 50 green beads, there is equal number of blue beads and green beads. How many beads does David have now?
| |
Blue |
Green |
| Before |
3 u |
1 u |
| Change |
- 10 |
+ 50 |
| After |
3 u - 10 |
1 u + 50 |
The number of blue beads and green beads in the end is the same.
3 u - 10 = 1 u + 50
3 u - 1 u = 50 + 10
2 u = 60
1 u = 60 ÷ 2 = 30
Number of beads that David has now
= 3 u - 10 + 1 u + 50
= 3 u + 1 u - 10 + 50
= 4 u + 40
= 4 x 30 + 40
= 120 + 40
= 160
Answer(s): 160
