m-motanul Tom
c- cățelul Jack
X- lungimea drumului
{[(X×3/10) ×2/7 ]×1/3 }:2=5
[(X×3/10) ×2/7 ]×1/3 =5×2
[(X×3/10) ×2/7 ]×1/3 =10
(X×3/10) ×2/7=10/1:1/3
(X×3/10) ×2/7=10/1×3/1
(X×3/10) ×2/7=30/1
X×3/10=30/1:2/7
X×3/10=30/1×7/2
X×3/10=15×7 totul supra/1×1
X×3/10=105/1
X=105/1 : 3/10
X=105/1 ×10/3
X=35×10 totul supra/1×1
X=350/1
X=350 ( deci lungimea drumului parcurs de motanul Tom este de 350 km)