Power = Δw/Δt
or
Power = Δe/Δt
*in this case you are only given the force, distance and the time. I would solve for the work and then plug that value into the first power formula listed.
W = F * distance
w = 100 * 5
W = 500
so.......
Power = Δw/Δt
P = 500/4.00
P = 125 <-- that is the answer
hope this helps :)