(20%) Use only primitive rules of inference to construct a derivation for this argument: "AvB; therefore,( A)& (B))." (Hint: Think about what would be the last step you need to derive ~X, and solve backwards.) (20%) Use only primitive rules of inference to construct a derivation for this argument: "(A)&B); therefore (AvB)." (Hint: The derivation for this is quite similar to the derivation for the previous problem.)