A baker 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?