= Chazbro Solutions uses flexible budgets based on the following data: Sales commissions = 8% of sales Advertising expense = 15% of sales Office salaries (Selling & Admin) expense = $50,000 per month Customer support expense = $20,000 per month + 30% of sales Research and development expense = $75,000 per month Total Selling and Administrative expenses will be if sales are $500,000 and will be $390,000 and $510,000, respectively. $365,000 and $480,000, respectively. $410,000 and $542,000, respectively $ 360,000 and $492,000, respectively. if sales are $750,000, respectively