From Mechanics

The forces on the particle are in equilibrium as the particle is at rest.

The sum of the forces in the normal direction (resolving in the normal direction)

\displaystyle \begin{align} & R-mg\cos {{20}^{\circ }}=0 \\ & \\ & R=mg\cos {{20}^{\circ }}=20\times 9\textrm{.}8\times 0\textrm{.}94=184\ \text{N} \\ \end{align}