CompuWorld sells two products, R66 and R100, and calculates sales variances using the contribution margin. Pertinent data for the current year follow: Selling price Variable cost per unit Contribution margin Fixed cost per unit Operating income Sales in units What is the R100 sales mix variance? Sales mix variance Budgeted Actual R66 R100 R66 R100 $ 50 40 $ 160 90 $ 55 43 $ 155 95 $ 10 6 $ 70 30 $ 12 $ 60 5 25 $ 4 $ 40 $ 7 $ 35 1,200 400 1,000 1,000