Question 240735
First lets convert km/hour to km/min
{{{(50km/hour) * (1h/60min) = 5km/6min}}}
Now we know that it took 10min going 50km/h. 
So if we take the {{{5km/6min}}} and multiply it by 10 min, you will get the distance traveled.

{{{(5km/6min)*10min = (50/6) km}}}

Lets convert 40km/h to km/min
{{{(40km/hour) * (1h/60min) = 2km/3min}}}
To find the time, divide the distance by the speed

{{{((50/6)km) / (2km/3min) = 12.5min}}}

It will take 12.5min