9 Shanchez Sunglasses sells 240 pairs of its best-selling sunglasses at $250 each per month. Following an increase in price to $280, Shanchez Sunglasses discovers that the quantity demanded falls to 215 units per month. a Calculate the price elasticity of demand for Shanchez Sunglasses' best-selling sunglasses. [2 marks] b Using your answer from Question 9a above, explain how knowledge of price elasticity of demand (PED) can be of use to Shanchez Sunglasses. [4 marks] 10 With the use of appropriate examples, analyse the factors that determine the value of price elasticity of demand (PED). [6 marks]