A firm's output, variable costs, and total costs are given in the table below. Instructions: Round your answers to the nearest dollar. a. Calculate marginal cost using the formula given in the chapter: A total cost / A quantity. Quantity Variable cost ($) Total cost ($) Marginal cost ($) 100 1 40 140 2 70 170 110 210 160 260 240 340 b. Calculate A variable cost / A quantity. A variable cost / 4 Quantity Variable cost ($) Total cost ($) quantity ($) 100 40 140 2 70 170 W 110 210 160 260 240 340