Here are total cost formulas, average variable, marginal cost, and more, (work out your own algebra to find alternatives): Average Total Cost (ATC) = Total Cost / Q (Output is quantity produced or ‘Q’).Average Variable Cost (AVC) = Total Variable Cost / QAverage Fixed Cost (AFC) = ATC – AVC.ere are total cost formulas, average variable, marginal cost, and more, (work out your own algebra to find alternatives): Average Total Cost (ATC) = Total Cost / Q (Output is quantity produced or ‘Q’).