Karl, he says you owe him a 15, you say 5... He offered to settle on 10 I believe (correct me if I'm wrong please @Caizier ), settle it and compromise. Drop your ego and make a business decision to settle this. We all have to do these kinds of things some times. I'm sure both of you still feel like you are not getting exactly what was written in the original deal. COMPRIMISE
I agree