economics question

4) The inverse demand function in an industry is p() = 20-y. The marginal cost of a unit of output is $8. a) What will total profits be if there is one firm in the market (monopoly)? b) What will total profits be if there are two Cournot duopolists (simultaneous decision on quantity)? c) What will total profits be if there are two firms where one is a quantity leader (Stackelberg model)