Econ 405 question

(9ts) Two firms A and B are engaged in an advertising contest. Each firm can choose its advertising ending a 2 0 and b 2 0. Given their ad spendings a, b, Firm A's profit equals Ta = 9a - a- - ab and Firm B's profit equals Th = 12b- b- - ab (3pts) Find firm A's best response function, namely find A's optimal strategy a as a function of B's rategy b. ) (3pts) Find firm B's best response function. ) (3pts) Use the two best response functions to find the Nash equilibrium