Answer
The direction of the force is $~~-11.3^{\circ}$
Work Step by Step
We can find the electrostatic force in unit-vector notation:
$F = q~E$
$F = (8.00\times 10^{-5}~C)~(3000~\hat{i} - 600~\hat{j})~N/C$
$F = (0.240~\hat{i} - 0.048~\hat{j})~N$
We can find the direction of the force as an angle $\theta$ below the positive x axis:
$tan~\theta = \frac{0.048}{0.240}$
$\theta = tan^{-1}~(\frac{0.048}{0.240})$
$\theta = 11.3^{\circ}$
The direction of the force is $~~-11.3^{\circ}$.
