Prove the identity of each of the following Boolean expressions, using algebraic manipulation:

a) ABC' + BC'D' + BC + C'D = B + C'd

b) WY + W'YZ' + WXZ + W'XY' = WY + W'XZ' + X'YZ' + XY'Z

c) AD' + A'B + C'D + B'C = (A'+B'+C'+D') (A + B + C + D)

any help at all would be greatly appreciated. Even if it's just a starting hint or soemthing.