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Insert Design Layout References Palatino Linoty... - 10 - A- A- A - B I U abe X, x? A. . Arthur's Plumbing reported the following: Revenues Variable manufacturing costs Variable nonmanufacturing costs Fixed manufacturing costs Fixed nonmanufacturing costs $4,500 $ 900 S810 $ 630 $ 545 Required: a. Compute contribution margin. b. Compute contribution margin percentage. c. Compute gross margin. d. Compute gross margin percentage. e Compute operating income. Sales total $400,000 when