I assume that the force of 20 N is applied along the direction of motion and was applied for the whole 6 meters, the formula of work is this; Work = force * distance * cosθ where θ is zero degrees. Plugging in the data to the formula; Work = 20 N * 6 m * cos 0º.
Work = 20 N * 6 m * 1
Work = 120 Nm
Work = 120 joules
Hope this helps!
