As shown in the figure, a plane mirror is fixed at a height of $50 \mathrm{cm}$ from the bottom of tank containing water $\left(\mu =\frac{4}{3}\right)$. The height of water in the tank is $8 \mathrm{cm}$. A small bulb is placed at the bottom of the water tank. The distance of image of the bulb formed by mirror from the bottom of the tank is  ______ $\mathrm{cm}$.