For each of the following Boolean functions f, design a two-level gating network for f as a

Question:

For each of the following Boolean functions f, design a two-level gating network for f as a minimal sum of products.
(a) f: B3 → B, where f(x, y, z) = 1 if and only if exactly two of the variables have the value 1.
(b) f: B4 → B, where f(w, x, y, z) = 1 if and only if an odd number of variables have the value 1.