Answer:
 (a) FIFO
cost of ending inventory = $442.00
cost of goods sold = $486.00
 (b) LIFO
cost of ending inventory = $354.00
cost of goods sold = $566.00
 (c) weighted average cost 
cost of ending inventory = $391.00
cost of goods sold = $529.00
Step-by-step explanation:
(a) FIFO
cost of ending inventory 
cost of ending inventory = Number of Units left × Earliest Price
 = 34 × $13.00
 = $442.00
cost of goods sold (46 units sold during the year)
cost of goods sold : 20 units × $10 = $200
 26 units × $11 = $286
 Total = $486
(b) LIFO
cost of ending inventory 
cost of ending inventory : 20 units × $10 = $200
 14 units × $11 = $154
 Total = $354
cost of goods sold (46 units sold during the year)
cost of goods sold : 30 units × $13 = $390
 16 units × $11 = $176
 Total = $566
(c) weighted average cost
cost of ending inventory 
cost of ending inventory = Number of Units left × Average price
New Average Price = ((20 units × $10) + (30 units × $11)) / 50 units
 = $10.60
New Average Price = ((50 units × $10.60) + (30 units × $13)) / 80 units
 = $11.50
cost of ending inventory = 34 units × $11.50
 = $391.00
cost of goods sold (46 units sold during the year)
cost of goods sold = Number of Units Sold × Average price
 = 46 units × $11.50
 = $529.00
c