AE4-13 Contribution Margin [LO 3] Rhetorix, Inc. produces stereo speakers. The selling price per pair of speakers is $1,600. The variable cost of production is $544 and the fixed cost per month is $67,400. Calculate the contribution margin associated with a pair of speakers. $ In August, the company sold 7 more pairs of speakers than planned. What is the expected effect on profit of selling the additional speakers? $