2.2.17 Derivatives and differentials

Problem: Calculate the partial derivatives of the function of three variables, given parametrically: \[ \begin{array}{l} u=\ln (2 x-\sqrt{z})+\frac{1}{5} \tan ^{-1} \frac{y}{x} \\ x=x(s), y=y(t), z=z(t, s) . \end{array} \]