How Many 12-Step paths are there from A to B

There are 60 paths from A to B.

The corner approach: https://drive.google.com/file/d/1_8ND-xHAqQUfnQiimEe09dafdEiixI0C/view?usp=sharing

$B = 78 + 78 = \boxed{156}$

https://web2.0calc.com/questions/help_42168

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