A governmental planning agency wishes to determine the sources of purchase of fuel for use by n depots from among m bidders.

a) Suppose that the maximum quantity offered by bidder i is ai gallons and that the demand of depot j is bj gallons. Let Cij be the unit delivery cost for bidder i to the jth depot.

b) Suppose that a discount in the unit delivery cost is offered by bidder i if the ordered quantity exceeds the level ui. How would you incorporate this modification in the model?