David, Lee and Bobby had the same number of balls. Bobby gave 0.6 of his balls to Lee. Then Lee gave 0.25 of his balls to David. Finally, after Lee gave 22 balls to Bobby, he had the same number of balls as Bobby. How many balls did Bobby have at first?
| |
David |
Lee |
Bobby |
| Before |
1 u |
1 u |
1 u |
| Change 1 |
|
+ 0.6 u |
- 0.6 u |
| After 1 |
1 u |
1.6 u |
0.4 u |
| Change 2 |
+ 0.4 u |
- 0.4 u |
|
| After 2 |
1.4 u |
1.2 u |
0.4 u |
| Change 3 |
|
- 22 |
+ 22 |
| After 3 |
1.4 u |
1.2 u - 22 |
0.4 u + 22 |
Number of balls that Lee gave to David
= 0.25 x 1.6 u
= 0.4 u
The number of balls that Lee and Bobby had in the end is the same.
1.2 u - 22 = 0.4 u + 22
1.2 u - 0.4 u = 22 + 22
0.8 u = 44
1 u = 44 ÷ 0.8 = 55
Number of balls that Bobby had at first
= 1 u
= 55
Answer(s): 55
