Consideram X lungimea totala a drumului.
Prima zi
[tex] \frac{1}{2} [/tex]*X kilometri parcursi
A doua zi
[tex] \frac{1}{3} [/tex]*X kilometri parcursi
A treia zi
120 kilometri parcursi
X=[tex] \frac{1}{2} [/tex]*X+[tex] \frac{1}{3}[/tex]*X+120
120=[tex] \frac{6X}{6} [/tex]-[tex] \frac{3X}{6} [/tex]-[tex] \frac{2X}{6} [/tex]
120=[tex] \frac{X}{6} [/tex]
X=6*120=720 de kilometri