The beginning inventory and purchases of an item for the period were as follows: Beginning inventory 10 units at $70 each First purchase 7 units at $75 each Second purchase 20 units at $80 each Third purchase 18 units at $85 each The company uses the periodic system, and there were 19 units in the inventory at the end of the period. Determine the cost of the 19 units in the inventory by each of the following methods, presenting details of your computations: (a) first-in, first-out; (b) last-in, first-out; (c) average cost.