A bullock cart has to cover a distance of 80 km in 10 hr.  If it covers half of the journey in $\frac{3}{5}$th time, what should be its speed to cover the remaining distance in the left time?

Distance $=80km$

Time $=10hr$

If it covers half of distance i.e., $80\times \frac{1}{2}=40km$ in $\frac{3}{5}$th of time

i.e., $10\times \frac{3}{5}=6$ hours then

remaining distance $=40km$ i.e., $[80-40]$

remaining time $=4hr$ i.e., $[10-6]$

Speed $=\frac{d}{t}$

$=\frac{40}{4}$

$=10kmph$.