I am not able even after a whole hour spent on figuring this out to understand the following passage. Please, can you help me out somehow? It is part of the explanation of how a tax affect a monopoly. We start by the assumption that marginal revenue equals margina cost (plus the tax):
$$a-2by = c+t$$
and we solve for y which leads to:
$$y=\frac{a-c-t}{2b}$$
Than I don't understand how I can get to this: $$\frac{\Delta y}{\Delta t}=- \frac {1}{2b}$$
and finally I don't understand why the demand is: $$p(y)=a-by$$
Thanks for the help in advance!