Eric Brown is responsible for upgrading the wireless network for his employer. He has identified seven possible locations to install new nodes for the network. Each node can provide service to different regions within his employer's corporate campus. The cost of installing each node and the regions that can be served by each node are summarized here:

Node 1: Regions 1, 2, 5; Cost: $700

Node 2: Regions 3, 6, 7; Cost $600

Node 3: Regions 2, 3, 7, 9; Cost $900

Node 4: Regions 1, 3, 6, 10; Cost $1250

Node 5: Regions 2, 4, 6, 8; Cost $850

Node 6: Regions 4, 5, 8, 10; Cost $1000

Node 7: Regions 1, 5, 7, 8, 9; Cost $100

a. Formulate an ILP for this problem.

b. Implement your model in a spreadsheet and solve it.

c. What is the optimal solution?