"All of the answers are adequate." and "All the answers are adequate."
The above statement is incorrect. You should say:
"Any answer will do."
Apart from that, without the context I can't really help. If you're talking about multiple choice then: "All answers are correct."
Usually we say:
"All the answers."
"All of them."
However, you can also say: "All of the answers." Tough, huh?