1. The problem statement, all variables and given/known data A screenshot of the problem: imgur link: https://i.imgur.com/ljtoclm.png 2. Relevant equations 3. The attempt at a solution My first attempt at the solution was this: imgur link: https://i.imgur.com/TJcvOzy.jpg However, I have access to the worked solution, and it is this: imgur link: https://i.imgur.com/u0BeWiZ.jpg I understand the worked solution. What I don't understand is what is wrong in my thinking/understanding so far as my original attempt at the solution goes? Is it not valid to use a Norton Equivalent where I tried to use one? If so, why not?