Gotham City must determine how to allocate ambulances during the next year. It costs $5000 per year to run an ambulance. Each ambulance must be assigned to one of two districts. Let xi be the number of ambulances assigned to district i, i = 1; 2. The average time (in minutes) it takes for an ambulance to respond to a call from district 1 is 40 - 3x1; for district 2, the time is 50 - 4x2. Gotham City has three goals (listed in order of priority):

Goal 1: At most $100; 000 per year should be spent on ambulance service.

Goal 2: Average response time in district 1 should be at most 5 minutes.

Goal 3: Average response time in district 2 should be at most five minutes.

a. Use goal programming to determine how many ambulances to assign to each district.

b. How does your answer change if Goal 2 has the highest priority, then Goal 3, and then Goal 1?