Logic Proofs

Please help me solve these proofs

a)

1. (~Yv(WvS))

2. ~S

3. (X->~(Y->W)) .: ~X

b)

1. ~(P.F)

2. [((WvL)->P).W]

3. (L->F)

c)

1. (A->(D->E))

2. (F->((A.B)v(A.~B))) :. ((F.D)->E)