game theory

Consider a partnership effort game with two players. Player 1 chooses effort level x and player 2 chooses effort level y, where x and y are both between 4 and 29. Players make their effort choices simultaneously, and payoffs are given by: u1(x,y) = 2xy - x2 U2(x,y) = 2xy -2y - y2 There is a unique Nash equilibrium of this game, in which both players choose the same effort level. What is this effort level? Give your answer to the nearest whole number