I'm having difficulty with the question in the pic provided. (http://i.imgur.com/Fg7CHoY.png). Basically the equation im given is dy/dx = (y-4x)/(x-y) and it walks through the steps needed to solve it, however, im supposed to show how to arrive at each step given. I've gotten part a, where it asks to show that the above equation can be written as dy/dx = (y/x - 4)/(1-y/x) and, introducing v=y/x, rewrite dy/dx in terms of v, x, and dv/dx. What I get for part b is dy/dx = d(xv)/dx = x(dv/dx) however, on part c, it looks like I'm supposed to get dy/dx = v+x(dv/dx) I'm not sure where the additional v term comes from. If anyone could help me out, i would really appreciate it!