31 A manufacturing company, Co.X, has supplied the following data: Tons of cement produced and sold Sales revenue 310,000 $ 1,014,000 Variable manufacturing expense 239,000 Fixed manufacturing expense $ 334,000 Variable selling and administrative expense $ 186,880 Fixed selling and administrative expense $ 100,000 Net operating income 154,120 The company's contribution margin ratio is closest to: 67.1% 43.5% 58.0% 15.2%