Answer
$$
F_R=-10 \mathrm{kN}
$$
Work Step by Step
Summing the forces acting on the plate,
$$
\begin{aligned}
& \left(F_R\right)_y=\Sigma F_y ; \quad F_R=-5 \mathrm{kN}-2 \mathrm{kN}-3 \mathrm{kN} \\
& =-10 \mathrm{kN}
\end{aligned}
$$
The negative sign indicates that $\mathbf{F}_R$ acts along the negative y axis.
