Point charges $Q_1=2\mathrm{.}0C$ and $Q_2=4\mathrm{.}0C$ are located at

vec$(r{)}_1=(4\mathrm{.}0$hat$(i)-2\mathrm{.}0$hat$(j)+5\mathrm{.}0$hat$(k))m$ and vec$(r{)}_2=(8\mathrm{.}0$hat$(i)+5\mathrm{.}0$hat$(j)-9\mathrm{.}0$hat$(k))m.$ What

is the force of $Q_2$ on $Q_1?$