Let yj, j=1...5, denote the binary variables representing the decision whether to open an emergency vehicles station in area j. How would you express the constraint that there should be at least one station that has a response time not greater than 8 minutes in area 2? Let yj, j=1...5, denote the binary variables representing the decision whether to open an emergency vehicles station in area j. How would you express the constraint that there should be at least one station that has a response time not greater than 8 minutes in area 2? y1 + y3 + y5 >= 2 y2 >= 1 y1 + y2 + y5 >= 1 y1 + y2 + y5 >= 1