Identify each cost below as variable (V), fixed (F), or mixed (M), relative to units sold Explain the reason for your answer. Units Produced 100 500 1,000 Total electric cost $1,500 $1,650 $1,700 Supervisor's monthly salary $4,500 $4,500 $4,500 Assembly line workers' per hour $30 $30 $30 wage rate Total materials cost $800 $4,000 $8,000 Depreciation on factory $5,000 $5,000 $5,000 equipment Total delivery costs $1,400 $1,800 $2,250