Răspuns :
prima zi=x
a doua zi=y
a treia zi=z
y=6+x
z=6+y=6+6+x=12+x
x+y+z=108=>x+6+x+12+x=108=>3x=90=>x=90/3=>x=30
a doua zi=y
a treia zi=z
y=6+x
z=6+y=6+6+x=12+x
x+y+z=108=>x+6+x+12+x=108=>3x=90=>x=90/3=>x=30
x+(x+6)+(x+12)=108
3x=90
x=30km in prima zi
x+6=36 km in a doua zi
x+12 = 42 km in a treia zi