Brenda's Brakes manufactures three different product lines, Models X, Y, and Z The following per unit data apply: Selling price Direct materials Direct labour ($12 per hour) Model* $50 6 12 Variable support costs ($4 per machine hour) 4 Model Y $60 6 18 6 10 Model Z $70 6 24 8 10 Fixed costs Required: 10 If there are a limited number of direct labour hours available and demand exceeds the total direct labour hours available, in what order should the models be produced to maximize total contribution margin?