ABC Ltd has provided the following data for its first three months of operations:

Month	Sales Revenue (£)	Purchases (£)	Operating Expenses (£)	Closing Inventory (£)
Jan	50,000	30,000	10,000	5,000
Feb	60,000	35,000	12,000	7,000
Mar	70,000	40,000	15,000	9,000

Requirements:

1. Calculate the Cost of Goods Sold (COGS) for each month.
2. Determine the Gross Profit for each month.
3. Prepare a quarterly income statement for the three months ended 31 March.