11) Julia's Catering has a monthly target operating income of $12,000. Variable expenses are 40% of sales and monthly fixed expenses are $9,000. a. What is the monthly margin of safety in dollars if Julia's Catering achieves its' operating income goal? b. What is Julia's operating leverage factor at the target level of operating income? O c. If the sales revenue increases by 15% in a month, by what percentage will the operating income increase