Find the derivative function \(f'\) for the function \(f\). Determine an equation of the line tangent to the graph of \(f\) at \(
(a,f
(a))\) for the given value of \
(a\). The function is \(f(x)=\frac{6}{5x+2}\) and the value of \
(a\) is -1. What is the derivative function \(f'\)? What is the equation of the line tangent to the graph of \(f\) at \((-1,f(-1))\)?