Not much to do here other than take the derivative using the formulas from class. \[f^{\prime}\left( t \right) = \frac{{5\ln \left( t \right) - \left( {1 + 5t} \right)\left( {\frac{1}{t}} \right)}}{{{{\left[ {\ln \left( t \right)} \right]}^2}}} = \require{bbox} \bbox[2pt,border:1px solid black]{{\frac{{5\ln \left( t \right) - \frac{1}{t} - 5}}{{{{\left[ {\ln \left( t \right)} \right]}^2}}}}}\]