Saluut!
Fie 4x nr de km parcursi in a doua zi.
Atunci in a treia zi a parcurs 2x si in prima zi x.
In total x + 4x + 2x = 7x;
Rezolvam ecuatia 7x = 77 => x = 11 => in prima zi a parcurs 11 km; in a doua zi a parcurs 44 km si in a treia zi a parcurs 22 km.
Bafta!