Question

A teacher pushed a 98 newton desk across a floor for a distance of 5 meter he exerted a horizontal force of 20 newton for four seconds

Answer 1

Missing question: "how much work is done by the teacher?" (found on internet)

Solution:
The work done to move the desk across the floor is equal to
$W=Fd$
where F is the horizontal force applied to move the desk, and d is the distance covered by the desk. If we use F=20 N and d=5 m, we find the work done:
$W=Fd=(20 N)(5 m)=100 J$