[The following information applies to the questions displayed below.] Westerville Company reported the following results from last year's operations: Sales Variable expenses Contribution margin Fixed expenses Net operating income $ 1,600,000 700,000 900,000 660,000 $ 240,000 Average operating assets $ 1,000,000 At the beginning of this year, the company has a $325,000 investment opportunity with the following cost and revenue characteristics: Sales Contribution margin ratio Fixed expenses $520,000 70 % of sales $ 312,000 The company's minimum required rate of return is 15%. Required: 1. What is last year's margin? Margin %