A cost that changes in total proportionately to changes in volume of activity is a(n): Differential cost. Fixed cost Incremental cost Variable cost. Product cost SBD Phone Company sells its cordless phone for $90 per unit. Fixed costs total $162.000. and variable costs are $36 per unit. How will the break-even point in units change in response to each of the following independent changes in selling price per unit. variable cost per unit. or total fixed costs? 1. Total fixed cost to $190.000 2. Variable cost to $34 per unit 3. Selling price per unit to $80 4. Variable cost to $67 per unit 5. Total fixed cost to $150.000 6. Selling price per unit to $120