4. Assume that the operating results for last year were as follows: Sales Less: Variable expenses Contribution margin Less: Fixed expenses Het operating income $2,460,000 615,090 1,845,690 922,580 $ 922,500 a. Compute the degree of operating leverage at the current level of sales. (Round your answer to 1 decimal place.) Degree of operating leverage b. The president expects sales to increase by 60% next year. By how much should nel operating income increase? Increase in operating income