Two duopoly quantity-setting firms selling bottles of spring water, Firm and Firm , face the market demand = 120 , where is price in pence and is quantity in bottles.

(a) Assuming that the owner of the spring does not charge either firm for the spring water that they bottle, what are the Cournot equilibrium quantities and prices for the two firms?

(b) Now assume that the owner of the spring charges Firm 10 pence per bottle and Firm 20 pence per bottle, what are the new Cournot equilibrium quantities and prices for the two firms?