Work done is given by product of force and displacement due to that force
So here we will have
[tex]Work = Force \times displacement[/tex]
here we know that
[tex]Force = 8 N[/tex]
[tex]displacement = 2 m[/tex]
Now work done is given as
[tex]W = 8\times 2 [/tex]
[tex]W = 16 J[/tex]
so it will do 16 J work to move the box