Surf Company can sell all of the two surfboard models it produces, but it has only 456 direct labor hours avalable. The Glide model requires 2 direct lobor hours per unit. The Ultra model requires 4 direct labor hours per unit. Contribution margin per unit is $256 for Glide and $412 for Uitra (a) Compute the contribution margin per direct labor hour for each product. (b) Determine the best sales mix and the resulting contribution margin