Fie distanta totala notata cu s:
zi1: s/2
zi2: s/2 :2 =s/4
zi3 : s/4 :4 = s/16
zi4: 12km si insumand avem
s/2 + s/4 + s/16 +12 = s
(8s+4s+s):16 +12 = s
16s-13s=12*16
3s=3*4*16
s=4*16=64km = lungimea totala
zi1 = s/2 = 32km
zi2 = s/4 = 16km
zi3 = s/4/4 =4km
zi4 =12km
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Verificare: 32+16 + 4 +12 = 64 OK.