TB 05-125 Neutron uses a periodic inventory system. Prepare.. Neutron uses a periodic inventory system. Prepare general journal entries to record the following transactions on the books of Neutron: z21. June10Neutron purchased merchandise on credit from Proton for $5,000, terms 2/10, n/30, FOB destination. Transportation costs of $250 were paid by Protorn. 12Neutron returned $900 of merchandise from the June 10 purchase 19 Neutron paid Proton for the June 10 purchase, less the return