Concept:Margin is profit expressed as a percentage of selling price, not cost price.Explanation:Average margin =20% means profit is 20% of sales.If sales =100, then cost of sales =100−20=80.Actual cost of sales is N720,000.Let sales be S. Then 80% of S=720,000.S=80/100720,000=N900,000.Profit =Sales−Cost of sales.Profit =900,000−720,000=N180,000.Answer:D. N180,000