In covering a distance of 30 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 choices:
A) 5 km/hr.  B) 3 km/hr.  C) 1 km/hr.  D) 7 km/hr.  E) 9 km/hr.
C   5 km/hr.   Let A's speed be X km/hr.   Then, 30/x - 30/2x = 3   6x = 30   x = 5 km/hr.
<result>A</result>
In covering a distance of 30 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: