Need help with weighted average method, thank you!

(a) LCM Trading has the following beginning inventory, purchases and sales of a particular product for the month of May: 1 May Beginning inventory 30 units at $30 each 4 May Purchase 70 units at $35 each 8 May Sale 60 units 10 May Purchase 60 units at $40 each 15 May Sale 25 units 20 May Sale 35 units 26 May Purchase 60 units at $50 each Using perpetual inventory system, compute the cost of goods sold for May and cost of the ending inventory on 31 May using the weighted average method