Perry, Justin and Luis had the same number of balls. Luis gave 0.6 of his balls to Justin. Then Justin gave 0.25 of his balls to Perry. Finally, after Justin gave 36 balls to Luis, he had the same number of balls as Luis. How many balls did Luis have at first?
| |
Perry |
Justin |
Luis |
| 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 |
|
- 36 |
+ 36 |
| After 3 |
1.4 u |
1.2 u - 36 |
0.4 u + 36 |
Number of balls that Justin gave to Perry
= 0.25 x 1.6 u
= 0.4 u
The number of balls that Justin and Luis had in the end is the same.
1.2 u - 36 = 0.4 u + 36
1.2 u - 0.4 u = 36 + 36
0.8 u = 72
1 u = 72 ÷ 0.8 = 90
Number of balls that Luis had at first
= 1 u
= 90
Answer(s): 90
