The distance covered by a train in (x+1) hours is (x2-1) km.  What is the speed of the train?

(x-1) km/h (x+1) km/h (x2-1) km/h (x+2) km/h

(x-1) km/h

Distance = Speed × Time (x2 - 1) = S × (x + 1) ⇒ S = \(\frac{(x - 1) (x + 1)}{(x + 1)}\) ⇒ S = (x - 1)