a and b starts from their house at 10am. they travek from their house on MG road at 20kmph and 40kmph. they meet at T junction at 12:00 pm B reaches the T junction earlier and turns right .Both of them continue travelling till 2:00pm what is distance between a& b at 2:00pm?

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Consider that the distance traveled by A till 12.00 noon is 
                d=s*t
                d=20*2//(12.00-10.00)
                  =40km

ie distance between xand y is 40.

so that the time taken by B to travel this 40 km is
                 t=d/s;
Therefore,
                 t=40/40;
Therefore,
                 t=1
so, B travelled xy in one hour(till 11.00) and in rest one hour (ie till 12),
and the distance travelled is 
                d=s*t; 
Therefore,
                d=40*1;
Therefore,
                 d=40
Hence, the distance between A and B is 40 km.