Denying the antecedent with P and Q:

• P -> Q

• ~P

• Therefore ~Q

Affirming the consequent with ~Q and ~P

• ~Q -> ~P

• ~P

• Therefore ~Q

Wow, I feel kind of bad just writing those chains of "deduction". Anyways, the same result was concluded from the same minor premise, the only difference is the major premise, and P -> Q and ~Q -> ~P are equivalent.

edit: formatting