An electron is placed in an $xy$ plane where the electric potential depends on $x$ and $y$ as shown in Fig. $5($the potential does not depend on $z).$ The scale of the vertical axis is set by $V_s=1000V.$ In unitvector notation, what is the electric force on the electron?

${\displaystyle \underset{?}{\overset{?}{}}}$

Fig. $5$