If a company locted in NJ sales some assets to a comapny located in NY, which state governs the laws of the transaction? I

Very complicated question based upon a branch of law called conflict of laws.  If contract does not say which law governs, then an analysis of which jurisdiction has the greatest interest in the case, where the contract is made and what the parties' expectations are must be made.     Starting point is where was contract made.  Analysis goes from there.