In the diagram, 91, 92, and q3 are in a straight line. Each of these particles has a charge of
-2.35 x 10-6 C. Particles qi and q2 are separated
by 0.100 m and particles q2 and q3 are separated
by 0.100 m. What is the net force on particle q3?
Remember: Negative forces (-F) will point left
Positive forces (+F) will point Right

  concave means having an outline or surface that curves inward like the interior of a circle or sphere. so the mirror curves inward.

If its history of, then b) because a) implies only present day (now)

W= fd
where f is an applied force and d is the distance over which it is applied. when a parachuting skydiver is at constant velocity, he is experiencing "terminal velocity", the point at which his acceleration down is canceled out by air resistance. that means that the resisting force of the air is equal to his weight, but in the opposite direction. with this, we can solve for the work done by the force.
w = fd
w = (92.0)(9.81 m/s^2) (325)
w= 2.93 x 10^5 j
the value for work in this case is positive because it is pushing up on the skydiver, who has a downward force of gravity.
therefore the answer is 2.93 x 10^5 j