Contrapositive of p→(q→r) is logically equivalent to
p→(q→r)
(q→r)→∼p
p∨q→r
(q→r)→p
Contrapositive of p→(q→r) is
~(q→r)→∼p≡~[~(q→r)]∨(~p)≡(q→r)∨(~p)≡(~p)∨(q→r)≡p→(q→r)