Given,
The mass of the box, m=16.6 kg
The force exerted by Roy, F=99.1 N
The coefficient of friction between the floor and the box, μ=0.324
The distance for which Roy pushes the box, d=11.4 m
The work done is given by the product of the force exerted by a source and the distance for which the force was exerted.
Thus the work done by Roy is given by,

On substituting the known values,

Thus the work done by Roy is 1130 J