[tex]\it 8h+20min=8h+\dfrac{60min}{3}=8h+\dfrac{1h}{3}=\dfrac{25}{3}h\\ \\ \\ 9t\ - - - - - - - - - -\ \dfrac{25}{3}h\\ \\ \\ 5t\ ----------\ \ x\ h\\ \rule{150}{0.7}\\ Avem\ propor\c{\it t}ionalitate\ invers\breve a\ \Rightarrow\ \dfrac{9}{5}=\dfrac{x}{\dfrac{25}{3}} \Rightarrow x=\dfrac{9\cdot\dfrac{25}{3}}{5}=\dfrac{9\cdot25}{3\cdot5}=15h[/tex]
