Spartan Systems reported total sales of $305,000, at a price of $25 and per unit variable expenses of $15, for the sales of their single product. Total Per Unit Sales $305,000 $25 Variable expenses 183,000 15 Contribution margin 122,000 $10 Fixed expenses 101,000 Net operating income $21,000 What is the amount of contribution margin if sales volume increases by 20%? rev: 03_17_2015_QC_CS-11135 $122,000 $25,200 $146,400 $16,800.