3. Ann and Bob are the heads of marketing and R&D departments in a company, respec- tively. Ann determines the level a E [0, 1] of advertisement and Bob determines the quality b E [0, 1] of the product. The profit of the firm is 7 (a, b) = ab. Ann and Bob have shares sA > 0 and SB > 0 in the profit, repectively. The cost of advertisement is a for Ann, and the cost of product development is by for Bob where y > 2. Therefore, the payoffs of Ann and Bob are sAab-a and sBab-by, respectively. They take actions simultaneously. Find all the Nash equilibria in pure strategies. (10 pts)