Answer
$2NH_{4}Cl(aq)+ Ca(OH)_{2}(aq)\ -->\ 2NH_{3}(g)+ 2H_{2}O(l)+ CaCl_{2}(aq)$
Work Step by Step
$NH_{4}^{+}$ neutralizes $OH^{-}$, forming $NH_{3}$, which bubbles out of the solution, and liquid $H_{2}O$. Add a coefficient of two to $NH_{4}Cl$ because there are 2 $OH^{-}$ groups in each $Ca(OH)_{2}$ molecule so we need a $NH_{4}^{+}$ ion to neutralize each. Then add a 2 to $NH_{3}$ and $H_{2}O$ to balance the $NH_{4}^{+}$ and $OH^{-}$.
