I know the general rule is to do both equally with the same volume, i.e. do your weaker body part first, then do exactly same number of reps for the stronger. The rest will sort itself out, from the weaker part getting more load and the stronger part eventually not getting enough load to cause hypertrophy. Of course this depends on many factors, but if you want a quick fix, I guess you could do more on your weaker part, but I wouldn't recommend it.
I'm sure someone who knows more will chime in soon.