John, David and Jack had some balls. David had 60% less balls than John. David had ³₇ of Jack's. After John gave 230 balls to David, he had ¹₅ of what David had. How many more balls did Jack have than John in the end?

John	David	Jack
5x3	2x3
	3x2	7x2
15	6	14

	Jack	John	David	Total balls of  John and David
Before	14x2 = 28 u	15x2 = 30 u	6x2 = 12 u	21x2 = 42 u
Change		- 230	+ 230
After	28 u	1x7 = 7 u	5x7 = 35 u	6x7 = 42 u

Number of balls that David had less than John at first in percent
= 100% - 60%
= 40%

40% = ⁴⁰₁₀₀ = ²₅

John : David = 5 : 2

The number of balls that David had at first is repeated.  Make the number of balls that David had at first the same.  LCM of 2 and 3 is 6.

When John gave 230 balls to David, the total number of balls that David and John had at first and in the end remains the same.  Make the total number of balls that David and John had the same.  LCM of 21 and 6 is 42.

Number of balls that John gave to David
= 30 u - 7 u
= 23 u

23 u = 230

1 u = 230 ÷ 23 = 10

Number of balls that Jack had more than John in the end
= 28 u - 7 u
= 21 u
= 21 x 10
= 210

Answer(s): 210