Helpful Hardware sells windows ( 80% of sales) and doors ( 20% of sales). The selling price of each window is $780 and of each door is $1,380. The variable cost of each window is $535 and of each door is $1,080. Fixed costs are $2,072,320. The break-even point in units using the weighted-average contribution margin is: Muliple Choice 8.095 units: 6240 units 16,560 units. 8,230 units 11.201 unts