Problem Solving

On September $15$th$,$ Czarnetzky & Son, Inc. $("$Czarnetzky & Son"$)$ borrowed money from Equipment Finance Corp. $("$Equipment$")$ and granted Equipment a security interest in all equipment then owned and thereafter acquired. A proper security agreement was executed by the parties, and a proper financing statement filed in the appropriate office. On October $15$th$,$ after the retirement of Bill Czarnetzky, Sr$.,$ Czarnetzky & Son changed its name to Czarnetzky Equipment, Inc $("$Czarnetzky Equipment"$).$ On that same date, Czarnetzky Equipment borrowed money from Small Bank and granted Small Bank a security interest in all equipment then owned and thereafter acquired. On December $15$th$,$ and then three months later on March $15,$ Czarnetzky Equipment purchased some equipment from Del Mar Co$..$ Five days later, Czarnetzky Equipment went into liquidation proceeding. Who has priority in the equipment purchased on December $15$th and March $15$th$,$ and why?