18.31. At an activity level of 8,700 units, P Corporation's total variable cost is $653,109 and its total fi cost is $658,416. Assume that this activity is within the relevant range. Required: For the activity level of 8,800 units, compute: (a) the total variable cost; (b) the total fixed cost; (c) the total cost; (d) the average variable cost per unit, (e) the average fixed cost per unit; 4. (0) the average total cost per unit