jnu 2010 doubt

[divyajain]

can someone help me with these two questions!

[Dreyfus]

There r 72 ways to commute...

[divyajain]

how ?can u plz explain

[Granpa Simpson]

While going from A to C he can go A to B in 4 ways and from B to C in 3 ways..now while returning he cannot use the same bus route..so from C to B he can return in 2 ways and from B to A in 3 ways...so total number of ways= 4*3*2*3=72.