The Following Data Is Available for One of the Products

The following data is available for one of the products sold by Wild Optics Company,which uses the periodic inventory system:
At the end of December,Wild Optics had 25 units on hand.The 75 units sold created revenue of $13 each.Determine the amounts for the December 31 ending inventory,the cost of goods sold for December,and the gross margin for December for each of the inventory costing methods listed below.
$$\begin{array} { r l r } \text { Dec. } 1 & \text { On hand, } 10 \text { units at } \$ 8.00 \text { each } & \$ 80 \\5 & \text { Purchased 30 units at } \$ 7.80 \text { each } & 234 \\18 & \text { Purchased } 40 \text { units at } \$ 8.15 \text { each } & 326 \\24 & \text { Purchased 20 units at } \$ 8.25 \text { each } & 165 \\& \text { Available for sale during December-100 units } & \$ 805\end{array}$$ ?
$$\begin{array} {| l | l | l | l| } \hline& \text { Ending Inventory } & \text { Cost of Goods Sold } & \text { Gross Profit } \\\hline \text { a. Weighted average } & & & \\\hline \text { b. FIFO } & & & \\\hline \text { c. LIFO } & & & \\\hline\end{array}$$