A person is driving a car towards east at a speed of 80 km/hr. A train appears to move towards north with a velocity of $80\sqrt{3}$ km/hr to the person driving the car. Find the speed of the train as measured with respect to earth.

Question

$\begin{array}{1 1}160km/hr\\180km/hr\\260km/hr\\280km/hr\end{array}$