Equilibrium · Equilibrium constant and reaction quotient

$\ce{X2(g) + Y2(g) <=> 2Z(g)}$

$\ce{X2(g)}$ and $\ce{Y2(g)}$ are added to a 1 L flask and it is found that the system attains the above equilibrium at T(K) with the number of moles of $\ce{X2(g)}$, $\ce{Y2(g)}$ and Z(g) being 3, 3 and 9 mol respectively (equilibrium moles). Under these conditions of equilibrium, 10 mol of Z(g) is added to the flask and the temperature is maintained at T(K). Then the number of moles of Z(g) in the flask when the new equilibrium is established is . (Nearest integer).