Hello, I have a question regarding one of the questions on a sample exam I have for an upcoming test tomorrow. For question 2, I attempt to use the Kinetic Work Energy theorem to solve for the Work done by friction, but I don't get a correct answer. As you can see, I attempted certain things, but I feel as if I am missing a key concept. Could anybody solve this for me? Again, this is not a graded assignment, just a practice exam they gave us to help us review the material. Thanks! Note: sorry if I posted this in the wrong section, first time on this website!