The following static and flexible budget report was prepared for the sales manager of Earthworks Ltd for the fourth quarter of 2019: Static Budget (20,000 units) Budget Actual Variance Sales $ 500,000 $ 550,000 $ 50,000 Variable costs: Commisions (15% of sales) Advertising (20% of sales) Travel (10% of sales) 75,000 80,000 5,000 100,000 105,000 5,000 50,000 55,000 W 5,000 225,000 240,000 15,000 Fixed costs: Sales salaries Administrative salaries Total costs 120,000 120,000 75,000 75,000 195,000 195,000 $ 420,000 $ 435,000 $ 15,000 Flexible Budget (Actual sales 22,000 units) Sales $ Budget 550,000 $ Actual Variance 550,000 $ Variable costs: Commisions (15% of sales) 82,500 80,000 2,500 Advertising (20% of sales) Travel (10% of sales) 110,000 105,000 5,000 55,000 55,000 247,500 240,000 7,500 Fixed costs: Sales salaries 120,000 120,000 Administrative salaries 75,000 75,000 R 195,000 195,000 Total costs 442,500 $ 435,000 $ 7,500 Required: Assuming that the sales manager has control over sales and selling costs, a) Complete the budget report by indicating whether each variance is Favourable (F), Unfavourable (U) or Neither (N). (12 marks) b) Comment on the manager's performance. (2 marks) c) Explain why flexible budgets are useful. (1 mark)