EXERCISE $2\mathrm{.}42\mathrm{.}4$ Beginning inventory, purchases, and sales data for Commodity Y for June are presented below:Sales, June $9$ REQUIRED: $($a$)$ Assuming that the perpetual inventory system is used, costing by the moving average method, determine the cost of the inventory balance at $30$ June. Show clear workings. Work to the nearest cent. $($b$)$ Assuming that the periodic inventory system is used, costing by the weighted average method, determine the cost of the $15$ units in the physical inventory at $30$ June. Work to the nearest cent. $($c$)$ Determine the amount of the difference between the inventory cost in $($a$)$ and $($b$)$ and explain the reason for the difference.