21. Therefore, total variable cost for each coach was $ 300. 22. Taking on such a huge variable cost is not a smart proposition for us. 23. The relation between fixed cost and variable cost can be modelled by an analytical formula. 24. Fixed costs do not generally depend on the number of units, while variable costs do. 25. Variable costs , including the supplies and processes used to build cars, are more easily cut.26. An analytical formula of variable cost as a function of these factors has been derived. 27. This can help a company to become more flexible by transforming fixed into variable costs . 28. "The biggest piece of variable costs is in purchasing, but purchasing can't do it alone. 29. A firm that is shut down is generating zero revenue and incurring no variable costs . 30. The model works best in industries that have low variable cost of production or inventory.