Notăm prețul inițial cu x.
[tex]\it I)\ x+\dfrac{15}{100}x=\dfrac{\ 115^{(5}}{100}x=\dfrac{23}{20}x\\ \\ \\ II)\ \dfrac{23}{20}x+\dfrac{5}{100}\cdot\dfrac{23}{20}x=20286 \Rightarrow \dfrac{23}{20}x\cdot\Big(1+\dfrac{5}{100}\Big)=20286|_{\cdot\dfrac{20}{23}} \Rightarrow \\ \\ \\ \Rightarrow x\cdot\dfrac{105}{100}=882\cdot20\Rightarrow x=882\cdot20\cdot\dfrac{100}{105} \Rightarrow x= 16 800\ lei[/tex]
Prețul după prima scumpire:
[tex]\it \dfrac{23}{20}\cdot 16800=23\cdot840 = 19320\ lei[/tex]
