Answer and Explanation:
The computation is shown below;
Cost of goods available for sale 
Beg. inventory 50 units at $800 = $40,000 
Add: Purchases 80 units at $820 = $65,600 
Add: purchases 75 units at $840 = $63,000 
Add: purchases 90 units at $850 = $76,500 
Cost of goods available for sale $245,100 
 Now 
Total number of bicycles is 
 = 50 + 80 + 75 + 90 
= 295 
And, Number of bikes sold is 235. 
 A. FIFO assumption 
Cost of goods available for sale $245,100 
less: Ending inventory 60 at $850 ($51,000) 
Cost of goods sold $194,100 
 B.LIFO assumption 
Cost of goods available for sale $245,100 
Less Ending inventory 
(50 units at $800 + 10units at $820) -$48,200 
Cost of goods sold $196,900 
 C.Weighted average assumption 
 Cost of goods available for sale -$245,100 
Less: ending inventory 60 units at $830.85 ($245,100 ÷ 295) $49,851 
 Cost of goods sold $195,249 
 D. Gross Margin under FIFO 
 Sales $352,500 (1,500 × 235) 
 Less: Cost of goods sold $194,100 
Gros sMargin $158,400 
 E.Income tax expense under LIFO 
Sales $352,500 
Less: COGS $196,900 
GM $155,600 
Less: operating exp -$80,000 
Income beforetax $75,600 
Less: Tax expense (30% of $75,600) $22,680 
Net Income $52,920 
 So, Income tax expense under the LIFO method is $ 22,680. 
 F. Tax saving using LIFO instead of FIFO 
Gross margin under FIFO $158,400 
Less: operating expense -$80,000 
Gross margin under FIFO -$78,400 
less: tax expense 30% of $78,400-$23,520 
 Net Income $54,880 
 Tax saving is ($23,520 - $22,680 ) = $840.00