Answer:
a.

b. Repulsive force
Step-by-step explanation:
The computation is shown below:
a. The magnitude of the force is
Given that
Charge = 7.52nc
Location = 1.65m
Point charge = 4.10nC
Based on the above information,
As we know that

b. Now as it can be seen that both contains the positive charges so this represents the repulsive force and the same is to be considered