The Inverell Board of Education is taking bids on the city's four school bus routes. Four companies have made the bids in the table below. Suppose each bidder can be assigned only one route.

	Bids ($)
	Route 1	Route 2	Route 3	Route 4
Company 1	4,000	5,000	-	-
Company 2	-	4,000	-	4,000
Company 3	3,000	-	2,000	-
Company 4	-	-	4,000	5,000

Complete the following tasks:

(a) Formulate and solve an assignment problem to minimise Inverell's cost of running the four bus routes.

(b) What will be the total cost to the Inverell Board of Education?

(c) After the tender submissions, Company 3 became insolvent. Give the collapse of Company 3, a new business, Company 5, has been allowed to submit a late bid. As they are only a small company, they are only interested in Route 3 and have submitted a bid for $6,000. What will the collapse of Company 3 cost the Inverell Board of Education and how will the optimal solution in part a change?