Xavier and Yvette are the only two persons on an island. There are only two goods, nuts and berries. Xavier's utility function is U(Nx; Bx) = NxBx. Yvette's utility function is U(Ny; By) = 2Ny + By. Xavier has 3 berries and 8 nuts. Yvette has 6 berries and 8 nuts. In a competitive equilibrium for this island economy, how many units of berries will Xavier consume?