Răspuns:
900 km
Explicație pas cu pas:
Vom nota cu x lungimea totala a drumului.
[tex]I zi: \frac{1}{4} *x=\frac{x}{4}\\\\rest: x-\frac{x}{4}= \frac{4x-x}{4}= \frac{3x}{4} \\\\II zi: \frac{1}{3}*\frac{3x}{4} +200=\frac{x}{4} +200\\\\rest: \frac{3x}{4} -(\frac{x}{4} +200)=\frac{3x}{4}-\frac{x}{4}-200=\frac{3x-x}{4} -200=\frac{2x}{4}-200=\frac{x}{2}-200\\\\III zi:\frac{13}{25}*(\frac{x}{2}-200)=\frac{13x}{25*2} -\frac{13}{25}*200=\frac{13x}{50}-13*8=\frac{13x}{50}-104\\\\rest: \frac{x}{2} -200-(\frac{13x}{50} -104)=\frac{25x}{50} -200-\frac{13x}{50} +104=\frac{12x}{50}-96[/tex]
Insa restul inseamna cat a mers in ultima zi. Dar in ultima zi a mers 120
[tex]=>\frac{12x}{50}-96=120 => \frac{12x}{50}=120+96 => 12x=216*50 => x=\frac{216*50}{12} => x=900km[/tex]
Succes la scoala!
