Three point$-$like charges are placed as shown in the figure, $a=20\mathrm{.}0cm$ and $b=64\mathrm{.}0cm.$ The charge $(q_3)$ is placed half way on the $(b)$ side. Find the magnitude of the electric field at the top left corner. Let $q_1=-2\mathrm{.}20C,q_2=-2\mathrm{.}40C,$ and $q_3=+4\mathrm{.}80C.$

N$/$C