Given $\displaystyle {f{{\left({x}\right)}}}=\frac{{55}}{{x}}$ find:

(a)  the slope of the line tangent to the graph of $\displaystyle {f{{\left({x}\right)}}}$ at  $\displaystyle {x}=-{9}$ is Preview Question 6 Part 1 of 2  

(b)  the equation of the line tangent to the graph of $\displaystyle {f{{\left({x}\right)}}}$ at $\displaystyle {x}=-{9}$ is $\displaystyle {y}=$ Preview Question 6 Part 2 of 2