A 57.5-kg skateboarder starts out with a speed of 1.80 m/s. He does 80.0 J of work on himself by pushing with his feet against the ground. In addition, friction does -265 J of work on him. In both cases, the forces doing the work are nonconservative. The final speed of the skateboarder is 6.20 m/s. Solve symbolically for the change in the skater’s height, ∆h, in terms of ∆PE, m and any fundamental constant(s), if necessary.