Force is a vector that has both a magnitude and a direction. Similarly, displacement is also a vector. Work is the dot product or scalar product of the vectors representing force and displacement. It is given by W = F*d*cos x, where x is the angle between the force vector and displacement vector.
Here, the force of 16 N makes an angle of 24 degrees with the horizontal. The displacement due to the force is a 2.68 m in the horizontal direction. The work done by the applied force is 16*2.68*cos 24 = 39.17 J
The normal force does no work as cos 90 = 0
Similarly the gravitational force does no work.
The work done by the net force is 39.17 J