Sara tells Kate that she will give her $50 to clean her garage. When Kate is halfway done, Sara decides to revoke her offer. Is this a valid revocation?

No, because this is now a bilateral contract

Explanation:

If an offeree/ a promisee has started performing the said work, it becomes a bilateral contract between the offeror/ promisor and the offeree. It cannot be revoked until the completion of the performance.

A contract is an agreement between two or more people that is legally binding to both parties involved. It is usually oral or written and it is mutually bindings obligation. A contract contains the enforcer whicha can be a terms and conditions, an offer, a performance and others.

A bilateral contract is an agreement between two parties whereby both parties agrees to fulfill its own aspect of the bargain. Example is any sales agreement, a work agreement such as i eill pay you $70 dollars if you can supply me 2 crates of egg. A breach of contract is when either of the parties involved in the contract did not fulfilled his or her part of the contract e.g Offer by the promisor not fullfiled or Acceptance/ work by the promisee is not fulfilled.

the minoan civilization flourished in the middle bronze age on the island of crete located in the eastern mediterranean from c. 2000 bce until c. 1500 bce. with their unique art and architecture, and the spread of their ideas through contact with other cultures across the aegean, the minoans made a significant contribution to the development of western european civilization as it is known today. labyrinth-like palace complexes, vivid frescoes depicting scenes such as bull-leaping and processions, fine gold jewelry, elegant stone vases, and pottery with vibrant decorations of marine life are all particular features of minoan crete.  

so basically their unique way of ding arts, as well as architecture.

aliens are not real, the myth was created about 700 years ago because people found markings in the field of their crops. also, no there were no aliens on the moon.

hope this ! give brainliest!