We have the next diagram
First we need to obtain the force in the x-axis
[tex]Fx=F\cos (\theta)[/tex]
where F=100 and θ=40°
[tex]F_X=100\cos (40)=76.60N[/tex]
And the use the next formula for work
[tex]W=F\cdot d[/tex]
where F is the force, d is the distance and W is the work
in our case F=Fx and d=10
[tex]W=76.6\cdot10=766\text{ J}[/tex]
the work he did is 766 J
