Answer:
The work done by the 83.1 N force is 4687.5 J.
The magnitude of the work done by the force of friction is 1187.5 J.
Explanation:
Given:
Mass of the block,
kg
Force acting on it,
N
Angle of application of force,
°
Displacement of the block,
m
Coefficient of friction, 
Acceleration due to gravity,
m/s²
Work done by a force is given as:

So, work done by the constant force is given as:

Now, in order to find work done by friction, we need to evaluate friction.
For the vertical direction, the net force is zero as there is no vertical motion.
Therefore,

Frictional force is given as:

Now, friction acts in the direction opposite to the displacement. Thus, angle between frictional force and displacement is 180°.
Therefore, work done by friction is:

Negative sign indicates that frictional force is acting opposite to motion.
So, the magnitude of the work done by the force of friction is 1187.5 J.