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We assume that the friction force along the inclined plane is not significant.  Also we assume that the beam is pulled along the incline at a small speed and with a  negligible acceleration.
    Incline is 2 meters high and the length of the inclined on the ground is 2.5 meters.  So the skew or slope of the incline is 2/2.5 = 0.8 
      tan Ф = slope of incline,  where Ф = angle of incline.
      W = weight of the beam
      W Sin Ф = force required to pull the beam = 400 N
              W = 400 / √(1+0.8²) = 400/√1.64 = 312.35 Newtons