Use the dangerous formula (MC = P ( 1 + 1/η ) to address the following. Suppose that a manufacturer sells a product through an upscale boutique and, with a different brand name, through a discount retailer. The elasticity of demand at the boutique is -2, and at the discount retailer it is -3. If the optimal price at the boutique is $100, what price (PD) should be charged at the discount retailer?