When an automobile is being driven at v miles per hour, the average driver require D feet of visibility to stop safelv, where D =xi]|.i]li.=.5v2 + illdv. Sketch the graph of Div]. The owner of a toy store can obtain a popular board game at a cost of $15 per set. She estimates that if each set sells for 3: dollars, then SHIF- 11 sets will be sold each week. a. Express the owner's weeklv prot from the sales of this game as a function of price. b. Graph this function, and estimate the optimal selling price. c. How manv sets will be sold each week at the optimal price