I'm not certain exactly what the inquiry pertains to.  The equation which is being solved has four variables and choosing a particular variable leads to algebraic manipulations.  In your equation 'w' is being solved for and clicking on a particular step allows you to review the logic which is provided. 

I always like to encourage users to click on the 'Options' tab and being solutions with 'a few steps', then increase the number of steps if/when the additional detail is helpful.  The following images show a couple of key points: