Are the following three arguments valid or invalid? Use any method, but show your work.

(a)

1.(~PQ)(~P&Q)

2.QP/~Q

(b)

1. ~(P&~Q)~P/(~QP)(~Q~P)

(c)

1.~(AB)~C

2. ~ (~A&~C)~B

3. ~ (BD)

4. B(E& ~A)/~AC