Night Shades Inc. (NSI) manufactures biotech sunglasses. These sunglasses sell for $150 each, and cost $70 each to produce. Night Shades Inc. has fixed costs of $100,000. a. Calculate Night Shades' Breakeven point. b. how much profit (loss) will Night Shades have if it sells 500 sunglasses? 4,000 sunglasses? c. Night Shades' manager expects an operating profit of $200,000. How many sunglasses must be sold to attain this profit