us company manufactures air-conditioning units for commercial buildings and has noticed considerable variation in shipping expenses from month to month as per the data below. Units Shipped Month January February arch April May Total Shipping Expense $ 2,160 3,060 2.55 July 8. If the air conditioners have an average sales price of $6.900. variable manufacturing costs are $3.450 per unit, variable manufacturing overhead is $1380 per unit and variable selling and administration costs excluding shipping) are $280 per unit what is the contribution margin per unit? Contribution margin per unit