Answer:

Explanation:
The magnitude of the electric field between two parallel conducting plates is defined as:

Here
is the potential difference between the plates and d its separation.
The electric potential energy is defined as the product between the particle's charge and the potential difference:

Solving for
and replacing in the electric field formula:

In this case we have a double charged ion, so
:

Step 2: calculate A and B magnitudes
Step 3: calculate x, y components
Step 4: sum vector components
Step 5: calculate magnitude of R
Step 6: calculate direction of R