Let $f(x) = \frac{3}{2\pi - 7 x}$.
Then the slope of the tangent line to the graph of $y=f(x)$ at the point $\left(\pi,-\frac{3}{5\pi}\right)$
is the limit as $x$ tends to of the following expression .

The value of this limit is .

It follows that the equation of the tangent line is $y =$ .