A person pushes a 10 kg cart a distance of 20 meters by exerting a 60 Newton horizontal force.
The frictional resistance force is 50 Newtons.
(a) How much work is done by each force acting on the cart?
(b) How much kinetic energy does the cart have at the end of the 20 meters if it started from
Rest?

Work is equal to the force applied times the distance the object moves in the direction of that force. With that you should be able to solve (a)

For (b) the principal that work applied = change in energy allows you to determine the change in energy of the car due to these opposing forces.