Question 987974
.
{{{380/4}}} = {{{570/t}}}, 


where t is unknown time.


Hence, 


t = {{{(570*4)/380}}} = {{{(3*4)/2}}} = 6 hours.


Or,  in other words:


The average velocity is  {{{380/4}}} = 95 {{{km/h}}}. 


Hence,  the unknown time is  {{{570/95}}} = 6 hours,  the same answer.