A cost driver is a measure of activity or volume level; increases in a driver cause variable/total costs to decrease. A learning curve is the rate at which labor hours per unit decrease as the volume of activity decreases. The decision rule is to accept the special order if: Price lessthanorequalto Relevant Variable Costs + Relevant Fixed Costs + Opportunity Cost. Parametric models are used in the early design stages to get an idea of how much the product (or project) will cost, on the basis of a few physical attributes (such as weight, volume, and power). The breakeven point (BEP) is where total revenues exceeds total costs. liquidity, is having enough cash available to pay debts when they are