[tex]\it Fie\ x\ -\ pre\c{\it t}ul\ ini\c{\it t}ial\\ \\ x+30\%\ din\ x\ =\ 650 \Rightarrow x+\dfrac{30}{100}x=650|_{\cdot100} \Rightarrow 100x+30x=65000 \Rightarrow \\ \\ \Rightarrow 130x=65000|_{:10} \Rightarrow 13x=6500|_{:13} \Rightarrow x=500\ \ell ei[/tex]
