1. In one particle intense exercise routine, exercise A burns 1500 calories per 30 minutes, exercise B burns 2100 per 30 minutes, and, exercise C burns 1800 calories per 30 minutes for a 120 kg athlete. Formulate a constraint that will allow the athlete to help determine how many minutes he should spend on each exercise if he wants to burn an average of at least 1800 calories per 30 minutes of exercising. (Use A, B and C as the number of minutes spent on each exercise.) Other constraints, not asked for, would be required to determine the actual values of A, B and C.