A takes 8 hours more than the time taken by B to cover a distance of 160 km. If A doubles his speed. he takes 3 hours more than B to cover the same distance. The speed (in km/h) of B is:

Time taken by A = 8 hours more than B Distance = 160 km A doubles the speed, he takes 3 hours more than B. Let the speed be S_A and S_B According to the question, ⇒ 160/S_A – 160/S_B = 8......(1) ⇒ 160/2S_A – 160/S_B = 3 ⇒ 80/S_A – 160/S_B = 3 ....(2) Multiplying equation (1) by 1/2 we get, ⇒ 80/S_A – 80/S_B = 4 .....(3) Now, Substituting equation (2) and (3) we get, ⇒ 80/S_A – 160/S_B = 3 and 80/S_A – 80/S_B = 4 ⇒ 160/S_B – 80/S_B = 4 – 3 ⇒ 80/S_B = 1 ⇒ S_B = 80 km/h ∴ The speed of B is 80 km/h.