In September, Cullumber Industries sold 830 units of product. The average sales price was $ 40. During the month, fixed costs were $ 7,704 and variable costs were 70% of sales. (a) Determine the contribution margin in dollars, per unit, and as a ratio. (Round Contribution margin to O decimal places, e.. 5,275. Other all answers to 2 decimal places, eg. 52.75.) Contribution margin (in dollars) $ Unit contribution margin $ Contribution margin ratio 90