A and B walk around a circular track. They start at 1 p.m from the same point in the opposite directions. A and B walk at a speed of 4 rounds per hour and 6 rounds per hour respectively. How many times shall they cross each other before 4 p.m
Choose the correct choice from the following choices.
A) 15
B) 20
C) 25
D) 30
E) 35
Explanation:   Relative speed = (4+6)= 
<gadget id="calculator">(4+6)</gadget>
<output>10</output>
10 rounds per hour   So, they cross each other 30 times in three hours hence, they cross 30 times before 4 p.m   Answer: Option 30
<result>D</result>
A and B walk around a circular track. They start at 1 p.m from the same point in the opposite directions. A and B walk at a speed of 4 rounds per hour and 6 rounds per hour respectively. How many times shall they cross each other before 4 p.m