Use the Data Shown Below to Answer the Following Question(s)

Use the data shown below to answer the following question(s).
Suppose that an unincorporated township wishes to find the best locations for emergency rooms.Assume that the township is divided into smaller layouts and that transportation studies have estimated the response time for emergency vehicles to travel between each pair of layouts.The township wants to locate the emergency rooms so that all layouts can be reached within a 9-minute response time.
The table below shows the estimated response time in minutes between each pair of layouts: Define X_j = 1 if an emergency room is located in layout j,and 0 if not.
-Determine the objective function.