Pentru profit:
sum_back * (back - 1) > sum_lay * (lay - 1)
sum_lay * (1 - commission) > sum_back

Ca sa avem acelasi profit indiferent de rezultat:
lay / back < 1 - commission

2 ecuatii cu 2 necunoscute:
sub_back * (odds_back - 1) - sum_lay * (odds_lay - 1) = sum_lay * (1 - commission) - sum_back
sum_back + sum_lay = sum