Answer
$$\vec{E}=-11.4 \vec{i} - 6.0 \vec{j} + 4.8 \vec{k} [V/m]$$
Work Step by Step
the total force acting on the electron is lorentz force which can be determined by the following relation:
$$\vec{F_{tot}}=q(\vec{E}+\vec{v} \times \vec{B})$$
where:
$q$ is the charge of the electron
$\vec{E}$ is the electric field
$\vec{v}$ is the velocity
$\vec{B}$ is the magnetic field
and due to Newton's second law $$\vec{F}_{tot}= m \vec{a}$$
so
$$q(\vec{E}+\vec{v} \times \vec{B})=m \vec{a}$$
meaning that $$\vec{E}= \frac{m}{q}(\vec{a}-\vec{v} \times \vec{B})$$
plugging the numbers we find that
$$\vec{E}=-11.4 \vec{i} - 6.0 \vec{j} + 4.8 \vec{k} [V/m]$$
