Sandra uses the Perpetual, Weighted Average Cost method of valuing inventories. During the month of August 2011, the following inventory details were recorded: Opening balance 5 August 10 August 18 August 20 units valued at $2 each Purchase of 40 units at $2.20 each Sale of 30 units Purchase of 50 units at $2.40 each Sale of 25 units 23 August The value of inventory balance as at 31 August 2011 was: $126.00 $117.00 $131.00 $126.50