Let the distance be 'l'. Now the velocities of A, B are 5v, 6v. Time taken to cover distance l is t(A)=l/(5v) and t(B)=l/(6v). Given that A takes 36 minutes more than B i.e. tA-tB=36.
Which is l/v[1/5-1/6]=36, l/(5*6*v)=36. Hence l/(5v)=36(6). Therefore, time taken by A is 216 minutes.