Work is the amount of force acted upon over a distance. This can be computed by getting the product of force and distance traveled.
W = Fd
Where:
W = work (J)
F = Force (N)
d = distance (m)
So your problem gives you what you need to solve for work.
F = 35N
d = 4m
All you need to do is put that into the equation and solve for Work.
W = Fd
= (35N)(4m)
= 140 N.m or 140 J