Robert is licensed real estate broker who maintains an office and employs several real estate salespersons. John is also a licensed real estate broker, but is not employed by Robert. John has an arrangement where he rents a desk in Robert's office. Whenever John needed forms to use in his business, he used forms provided by Robert. These forms had Robert's business name at the top.
Robert placed an advertisement in a local newspaper for property that his brokerage had listed for a property owner. Martha, who was looking for a property to purchase, read the advertisement and called Robert to arrange a showing of the property. Robert told Martha that he was very busy with other matters at the moment and would be unable to show her any property, but that he would send out "one of his men."
The same afternoon John appeared at Martha's home. John showed the property to Martha, and Martha had John write an offer to purchase the property. John used a purchase offer form that had the name of Robert's firm on the top to prepare the offer. Martha signed the offer, and John gave Martha a copy. John told Martha to make out a check in the amount of $45,000 payable to him as an earnest money deposit on the purchase offer and told Martha that he would hold the check in the real estate office until the seller's accepted Martha's offer.
The next day, John cashed the check and both John and the cash disappeared. When Martha called Robert to ask whether her offer had been accepted by the seller's, Robert told Martha that he did not know that she had made an offer and had not seen John since he sent him to meet with Martha.
What is Martha's best argument that John is an agent of Robert, and what elements must she prove to establish this type of agency?