Sheridan Trivia Co. manufactures and sells two trivia products, the Square Trivia Game and the Round Trivia Game. Last quarter's operating prots, by product. and for the company as a wholel were as follows: Square Round Total Sales revenue $15,500 $6,610 $22,110 Variable expenses 4,830 2,990 7,820 Contribution margin 10,670 3,620 14,290 Fixed expenses 2,930 4,200 7,130 Operating income $ 7,740 ${580} $7,160