for number 5, how to calculate the weighted average?

Francine Company's ending inventory is composed of 50 units that had cost $20 each and 100 units that had cost $14 each. If the company can replace all 150 units at a cost of $15 each, determine the value that should be assigned to the company's ending inventory assuming that it applies LCM on an item by item basis. Precision Company uses the perpetual inventory method. It has provided the following inventory information for the month of May 2014: May 1 On hand, 20 units @ $25.00 each May 8 Purchased 100 units @ $34.60 each May 15 Sold 90 units @ $ 120.00 each May 24 Purchased 75 units @ $40.00 each May 29 Sold 65 units @ $ 130.00 each Determine Precision Company's Cost of Goods Sold for May 2014 using FIFO method. Determine Precision Company's Cost of Ending Inventory for May 2014 using Weighted Average method