x/(x-3)-2=m/(x-3)
x/(x-3)-m/(x-3)=2
(x-m)/(x-3)=2
x-m=2(x-3)
x-m=2x-6
6-m=2x-x
x=6-m
因为x有正数解,所以x>0
所以6-m>0
所以m