Surf company can sell all of the two surfboard models it produces, but it has only 468 direct labor hours available. The glide model requires 2 direct labor hours per unit. The ultra model requires 4 direct labor hours per unit. Contribution margin per unit is $268 for glide and $436 for ultra. (a) compute the contribution margin per direct labor hour for each product. (b) determine the best sales mix and the resulting contribution margin