3. Two fishermen fish in a lake, which has 70 fish in one year. They receive an annual payoff of: P. = S, X F, , where S, = spring catch and F, = fall catch, for fisherman i. Each fisherman chooses his spring catch; in the fall, the remaining fish must be shared equally by them. a) What is the best payoff each fisherman can earn individually? What is the best payoff each can get cooperatively