Answer:
The offer was accepted and a binding contract has been formed.
Step-by-step explanation:
The offeror (Bonnie) can revoke her offer anytime before the offeree has accepted the offer. In order for the revocation to take place, the offeree must have been notified about it.
The problem here is that before the offeree (Dale) was notified that the offer had been revoked, he had already accepted the offer. So a contract has already been formed.
In common law, the posting rule establishes that an offer is accepted as soon as it has been mailed to the offeror. So in this case, Dale accepted the offer on the 7th day, and was notified about the revocation on the 8th day. So the acceptance is prior to the revocation, therefore, the revocation is not valid. The posting rule only applies to the acceptance of the offer, not to the revocation of the offer.