Westerville Company reported the following results from last year's operations Sales Variable expenses Contribution margin Fixed expenses Net operating income Average operating assets $ 1,750,000 520,000 1,230,000 880,000 $ 350,000 $875,000 At the beginning of this year, the company has a $200,000 investment opportunity with the following cost and revenue characteristics Sales Contribution margin ratio Fixed expenses $ 320,000 60% of sales $ 128,000 lhe companys minimum required rate ot return is 20%