What are the rules Bilbo and Gollum agree to concerning the riddle contest?(ch.5)Its from a study guide I got from school and I'm in middle school...

In chapter five of The Hobbit, Bilbo
points a sword at Gollum after awakening from a dream and hearing Gollum hissing. Given
that Gollum does not wish to take on the sword, he decides to make a proposal to
Bilbo.

Gollum proposes they should have a match of wits.
Each will ask the other a riddle. The first one to fail to answer the riddle will
concede to the agreement given before the riddles
began.

Gollum states that if Bilbo stumps him then Gollum
will lead him out of the mountains. If Gollum is able to stump Bilbo, he gets to eat
him.

Bilbo, needing to escape the mountains, decides that
he has no other choice but to agree to Gollum's terms. Therefore, the pact is made and
each begins to give the other their riddles.

In the end,
Bilbo is able to stump, or rather trick, Gullom. Gollum fails at answering the riddle
and he is left with no other choice but to lead Bilbo out of the
mountains.