Diggins LTD had a beginning inventory of 200 units at a cost of $12 per unit on 1 August. During the month, the following purchases and sales were made.

Purchases
August 4 250 units at $13
August 15 350 units at $15
August 28 200 units at $14

Sales
August 7 150 units
August 11 100 units
August 17 300 units
August 24 200 units

determine the ending inventory balance and the value of cost of goods sold under:
a) weighted average method
b)fifo method

i tried this but i stil dont understand it properly
fifo especially like with the units in the balance

i got up to august 7th then after that i dont know how the units change in the balance


any help??
please