Engberg Company installs lawn sod in home yards. The company's most recent monthly contribution format income statement follows: Percent of Sales 100% Amount $ 138,000 55,200 B2,800 21,000 $ 61,800 Sales Variable expenses Contribution margin Fixed expenses Net operating income 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 13% increase in sales. 3. Construct a new contribution format income statement for the company assuming a 13% increase in sales