Answer:
The electric field strength at the midpoint of the line joining the charges is zero (0)
Step-by-step explanation:
Given that the two charges are both positive (same charge) and are equal in magnitude that is 6uC. The electric field strength at the midpoint of the line joining the two charges will be equal and opposite in magnitude, therefore they will cancel each other out and the electric field strength at this point will be equal to zero.