The torque acting on the nut is given as,
[tex]\tau=Fr[/tex]The work done on the nut can be given as,
[tex]W=\tau\theta[/tex]Substitute the known expression,
[tex]W=Fr\theta[/tex]Substitute the known values,
[tex]\begin{gathered} W=(250N)(0.75m)(45^{\circ})(\frac{3.14\text{ rad}}{180^{\circ}}) \\ =147.2\text{ J} \end{gathered}[/tex]Thus, the work done by person to rotate the nut is 147.2 J.