QUESTION B1 (7 marks total) Alice and Bob play the following extensive form game. There are two periods. Alice moves first in period 1 and chooses x1 E [0, 10]. In period 2, Bob observes Alice's action and chooses x2 E [0, 10]. The utility function of player i E { Alice, Bob} is ui(X1, (2) = xi(9 - x1 - X2) - x; if x1 + 22 19 and Wi(21, 22) = -Xi if 21 + 22 > 9. Find all subgame perfect equiliabria of this game. Show your work. Note that you need to find strategies for each player, just listing actions on the equilibrium path is not enough.]