From the formula of W = F·d , becuase we have the values for W and d we can find F
W = F·d
F= W/d
= 250/5
= 50 N
40 N of force was applied
We can't tell from the information you gave. Work = (force) times (distance), but that's the distance the force moves. It makes no difference how long the lever is, only how far the force moves.