The following information is available for Bluewood Corporation for a sales volume of 500 stereo speakers for the past month: Total Per Unit Sales $225,000 $450 Less: variable expenses 80,000 160 Contribution margin $145,000 $290 Less: fixed expenses $ 35,000 Net operating income $110,000 If sales increase by $51,750, net income will increase by what amount? $ 6,000 $ 8,000 $20,000 $33,350