Răspuns:
15 kilometri
Explicație pas cu pas:
Notam cu x lungimea traseului
[tex]x-\frac{2x}{3} = \frac{3x-2x}{3} = \frac{x}{3} \:\:restul\:\:din \:\:traseu\:\:dupa\:\:ce \:\:a \:\:parcurs \:\:doua\:\:treimi\\\\\frac{x}{3} = \frac{2x}{3} -5\\\\\frac{x}{3} = \frac{2x-15}{3}\\\\3x = 3*(2x-15)\\\\3x = 6x - 45\\\\3x+45 = 6x\\\\45 = 6x-3x\\\\45 = 3x\\\\x = 45:3\\\\\boxed{x=15\:km}[/tex]