In covering a distance of 90 km, A takes 2 hours more than B. If A doubles his speed, then he would take 1 hour less than B. A's speed is:	Choose the correct choice from the following answers:
A) 5 km/h B) 8 km/h C) 10 km/h D) 15 km/h E) 25 km/h
Let A's speed be X km/hr.   Then, 90/x - 90/2x = 3   6x = 90   x = 15 km/hr.   Answer : 15 km/h.
<result>D</result>
In covering a distance of 90 km, A takes 2 hours more than B. If A doubles his speed, then he would take 1 hour less than B. A's speed is: