Schneider's Bakery sells cakes. At a price of $20 per cake, it sells 300 cakes per week. At a price of $50, it sells 150 cakes per week. (a) (2.5 points) Find a linear demand function D(x) that models this situation. (b) (2.5 points) Find the elasticity of demand. (c) (2.5 points) Find E(20) and E(50), and explain what these numbers represent. (d) (2.5 points) Using the linear demand function from part (a), find the price x that results in unit elasticity, and explain what this number represents. Also, determine the weekly revenue at this price.