Please solve this question General accounting and step by step explanation

Assume the following operating results for last year: - Sales: $800,000 - Variable expenses: $400,000 - Contribution margin: $400,000 - Fixed expenses: $150,000 . Net operating income: $250,000 a. Compute the degree of operating leverage at the current level of sales. b. The president expects sales to increase by 12% next year. By how much should net operating income increase