A firm's output, variable costs, and total costs are given In the table below. Instructions: Enter your answers as a whole number. a. Calculate marginal cost using the formula given In the chapter: ATotal cost/AQuantity. Variable cost Quantity ($) Total cost ($) Marginal cost ($) 58 150 15 x 180 9 128 220 7 46 186 280 7 268 360 7 X b. Calculate AVariable cost/AQuantity. Quantity Variable cost Avariable cost ($)/ ($) Total cost ($) Quantity 50 150 5 28 80 189 4 30 128 228 4 48 189 280 4.5 260 360 5.2