Abaker makes cakes and sells them at county fairs. his initial cost for the fair was $45 to reserve a booth and $25 traveling expenses. he figures that it costs $1.75 to make each cake and he charges $6.50 per cake. let x represent the number of cakes sold. (a) express the revenue r as a function x. (b) express the cost c as a function of x. (c) how many cakes will he need to sell before he will make a profit?