Aman exerts a constant force to pull a 49-kg box across a floor at constant speed. he exerts this force by attaching a rope to the box and pulling so that the rope makes a constant angle of 36.9∘ above the horizontal. the coefficient of kinetic friction for the box-floor interface is μk = 0.20.

what is the work done by the man as he moves the box 10 m?

the velocity is constant so fnet=0 and
f horizontal=f friction
f horizontal=f man × cos36.9
f friction=0.2(9.8×49 - f up)
f up = f man × sin36.9

so
fm(cos36.9)=0.2(9.8×49 - fm(sin36.9))
solve for fm: 104.4 n

multiply by 10 to get 1044 that's wrong.