Answer:
V = 40 km/h
Explanation:
Total distance = 120 km
Constant speed of train = V km/h
⇒

Its given that if speed is reduced by 10 km/h , the time taken by train increases by 1 hour. BUT THE DISTANCE REMAINS SAME. So,






Factorise the quadratic equation.




Speed can't be negative. So , V = 40 km/h