Find the answer

Question

Two parallel train tracks runs from north to south .one track train A is moving from north to south with speed of 54 km per hour on the other track train B is moving South to North with speed of 90 km per hour find the relative velocity of a 1)b with respect to a

2) the ground with respect to b

3)a with respect to ground

Answer 1

1) 144 kph

2) the ground is not moving

3) 54 kph