Engberg Company installs lawn sod in home yards. The company's most recent monthly contribution format income statement follows: Sales Variable expenses Contribution margin Fixed expenses Net operating income Amount $ 143,000 57,200 85,800 15,000 $ 70,800 Percent of Sales 100% 40 60% Required: 1. What is the company's degree of operating leverage? 2. Using the degree of operating leverage, estimate the impact on net operating income of a 18% increase in unit sales. 3. Construct a new contribution format income statement for the company assuming a 18% increase in unit sales