Crane Cord Company produces replacement adapter power charger cords that it sells for $20 each. Each power charger cord costs $7 of variable costs to make. During April, 500 power charger cords were sold. Fixed costs for April were $4 per unit for a total of $2000 for the month. How much will Crane's operating income increase for each $1200 increase in monthly revenue? $780. Not enough information to determine the answer. $580. $400