simplify the following statements (so that negation only appears right before variables).
a. ⇁(P ⟶ ⇁Q)
b. (⇁P v ⇁Q) ⟶ ⇁ (Q ^ R)
c. ⇁ (( P ⟶ ⇁ Q) V ⇁(R ^ ⇁ R)).
d. it is false that if Sam is not a man then Chris is a woman, and that Chris is not a woman