Sam, Neave and David had the same number of balls. David gave 0.6 of his balls to Neave. Then Neave gave 0.25 of his balls to Sam. Finally, after Neave gave 26 balls to David, he had the same number of balls as David. How many balls did David have at first?
| |
Sam |
Neave |
David |
| 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 |
|
- 26 |
+ 26 |
| After 3 |
1.4 u |
1.2 u - 26 |
0.4 u + 26 |
Number of balls that Neave gave to Sam
= 0.25 x 1.6 u
= 0.4 u
The number of balls that Neave and David had in the end is the same.
1.2 u - 26 = 0.4 u + 26
1.2 u - 0.4 u = 26 + 26
0.8 u = 52
1 u = 52 ÷ 0.8 = 65
Number of balls that David had at first
= 1 u
= 65
Answer(s): 65
