Westerville Company reported the following results from last year's operations: Sales Variable expenses Contribution margin Fixed expenses Net operating income Average operating assets $ 1,900,000 550,000 1,350,000 875,000 $ 475,000 $ 1,187,500 At the beginning of this year, the company has a $237,500 investment opportunity with the following cost and revenue characteristics: Sales Contribution margin ratio Fixed expenses $ 380,000 50% of sales $ 133,000 The company's minimum required rate of return is 10%. Required: 1. What is last year's margin? Margin %