charlie roberts owns charlies pets, a small retail shop selling pet supplies, on december 31,2018 the accounting records of charlies pets showed the following: merchandise inventory on 12/31/2018 10300, merchandise inventory on 1/1/2018 15200, net sales revenue 51000, utilities expenses for the shop 4000, rent for the shop 4200, sales commission 2550, purchases of merchandise inventory 22000. prepare an income statement for the year ended 12/31/2018, 3800 units were sold. what was the cost per unit also?