Conf. definitiei Vmed=''drumul parcurs''/''timpul in care drumul a fost parcurs'',
deci t1=d/(3V1) si t2=2d/(3.50) , timpul total fiind t=t1+t2=d(1/(3V1)+2/150)
</Vitza medie fiind Vmed=d/t=1//(1/(3V1)+2/150)=37,5 sau; 37,5/(3V1)+
2.37,5/150=1 sau; 12,5/V1=1-1/2=1/2->V1=25km/h