The answer to the question is shown below:
We all know that formula for solving work done is the force multiplied by distance covered:
Work done = Force x distance
Distance = 5m
Force = 500 N
Work done = 500 N * 5m
Work done = 2500 J
∑F = ma = (90 kg)(1.2 m/s²) = 108 N = 100 N (1 significant digit)