$\begin{array}{l} P = \left( {1 - \dfrac{{x - 3\sqrt x }}{{x - 9}}} \right):\left( {\dfrac{{\sqrt x - 3}}{{2 - \sqrt x }} + \dfrac{{\sqrt x - 2}}{{3 + \sqrt x }} - \dfrac{{9 - x}}{{x + \sqrt x - 6}}} \right)\\ P = \left( {\dfrac{{x - 9 - x + 3\sqrt x }}{{x - 9}}} \right):\left( {\dfrac{{\left( {3 - \sqrt x } \right)\left( {\sqrt x + 3} \right) + {{\left( {\sqrt x - 2} \right)}^2} - 9 + x}}{{\left( {\sqrt x + 3} \right)\left( {\sqrt x - 2} \right)}}} \right)\\ P = \dfrac{{3\sqrt x - 9}}{{x - 9}}:\left( {\dfrac{{9 - x - 9 + x + {{\left( {\sqrt x - 2} \right)}^2}}}{{\left( {\sqrt x + 3} \right)\left( {\sqrt x - 2} \right)}}} \right)\\ P = \dfrac{3}{{\sqrt x + 3}}:\dfrac{{\sqrt x - 2}}{{\sqrt x + 3}}\\ P = \dfrac{3}{{\sqrt x - 2}}\\ b)P = 1\\ \Leftrightarrow \dfrac{3}{{\sqrt x - 2}} = 1\\ \Leftrightarrow \sqrt x - 2 = 3\\ \Leftrightarrow \sqrt x = 5 \Leftrightarrow x = 25 \end{array}$
