>>749
P((A∧B)|C)
=P((A∧B)∧C)/P(C)
=P(A∧(B∧C))/P(C)
=P(A|(B∧C))P(B∧C)/P(C)
=P(A|(B∧C))P(B|C)P(C)/P(C)
=P(A|B∧C)P(B|C)