A city wants to locate 2 new firefighting ladder trucks to maximize the number of tall buildings which they can cover within a 3 minute response time. The city is divided into 4 zones. The fire chief wants to locate no more than one of the trucks in either Zone 1 or Zone 2. The number of tall buildings in each zone and the travel time between zones is listed below No. tall buildings From zone 1 2 3 4 50 1 0 2 1 6 90 2 2 0 4 5 60 3 1 4 0 1 70 4 6 5 1 0 a) Formulate the IP for this problem. b) What is the optimal number of tall buildings that can be covered