Competing and cooperating Demand for Chilean copper is given by P = 150 Q, where Q is the total quantity of copper extracted by Chilean mining firms. Chile has just three copper mining firms, Antofagasta Inc.., Bisbee Corp. and Chiquicamata Corp. All these firms have the same costs of production given by c(qi) = 6qi where qi is the quantity of copper extracted by firm i. Antofagasta Inc. has a small mine and cannot extract more than 36 units of ore. Bisbee Corp and Chiquicamata Corp. are bigger and have extraction capacities of 75 units each. The three firms simultaneously decide the amount of copper they each extract. Each firm wants to maximize its own profit