B: Dad, A wants to jump 11 more times and I don't want her too.
Me: Well, lets go see what we can do about this.
Me to A: B says you want to jump 11 more times.
A: Well, he got to jump 5 times and said I can only jump 3 times. I want to do more than 5.
B: How about you jump 8 times?
A: I only want to jump 8 or 11 times, so 8 is perfect.
Completely and totally arbitrary numbers, but at least they solved their disagreement themselves. Parenting win!