use the work-energy theorem : The work done by all forces on an object = change in it's kinetic energy.
(1) you've got the final and initial velocities, so you can get the change in kinetic energy.
(2) all the forces here are constant, so you can directly use f.s
(3)the forces are the applied force, friction, weight and normal reaction.
(4) choose the coordinate system, preferably, with the an axis on the slope. You've also got the angle of the slope.
(5) you know the displacement. So, find out the work done by each force by using f.s = f.s.cos(angle between the f and s), and equate it to the change in kinetic energy.
You have one unknown, the force of friction, so one equation will take you through!