How come the work is positive and not negative?
no one knows
Hi thesouthportschool, the negative sign in that you're used to seeing is the work done by the electric field. Since, in this question, we're asked to find the work done by an external force, the external force is applying a force in the opposite direction to that of the electric field. For this reason the work done by the external force has a sign opposite to that of the electric field, which means with no negative sign.
Hope that helps,
Why is the potential energy not 0 when the charge is midpoint between the two 35μC charges? Is it not at static equilibrium?