A and B walk around a circular track. A and B walk at a speed of 4 rounds per hour and 5 rounds per hour respectively. If they start at 8 a.m. from the same point in opposite directions, how many times shall they cross each other before 10.30 a.m.?  Choose the correct choice from the following answers
A) 10	B) 20	C) 22	D) 9	E) 5
Relative speed = Speed of A + Speed of B (âˆ´ they walk in opposite directions)   = 4 + 5= 
<gadget id="calculator">4 + 5</gadget>
<output>9</output>
9 rounds per hour=&gt; They cross each other 9 times in 1 hour and 4 times in 1/2 hour   Time duration from 8 am to 10.30 am =2.5 hour   Hence they cross each other 22 times before 10.30 am   Answer : 22
<result>C</result>
A and B walk around a circular track. A and B walk at a speed of 4 rounds per hour and 5 rounds per hour respectively. If they start at 8 a.m. from the same point in opposite directions, how many times shall they cross each other before 10.30 a.m.?