A and B are adjacent to each other 12.

P (A and B are adjacent) = 12/42=2/7

There are 7*6=42 situations in station C and station D..

There are 30 cases where c and d are not adjacent.

P (C and D are not adjacent) =30/42=5/7

P (A and B are adjacent, C and D are not) =2/7*5/7= 10/49.