Find the number of paths from A to B (Each step can only go up or to the right.) https://latex.artofproblemsolving.com/3/2/6/326482219d74fa7b63711b2833862ccad0dc7b83.png
We have this possible set of moves from A to B [ R = right U = up ]
( R, R, R, R, R, U,U,U,U)
Since we can place te R's in any 5 of the 9 positions and still get from A to B....the number of total paths is
C(9,5) =
126
+128 
