From Mechanics

Vertically the forces on the tank are in equilibrium

\displaystyle \begin{align} & \uparrow \ R-mg=0 \\ & R=800\times 9\textrm{.}8=7840\ \text{N} \\ \end{align}

The maximum friction is thus,

\displaystyle F=\mu R=0\textrm{.}6\times 7840=4704\ \text{N}

This is less than the force exerted by the rope. Thus resultant horisontal force is

\displaystyle \leftarrow \ 5000-4704=296\ \text{N}