Frank, wishing to sell his car, put a sign in its window and parked it on the street outside his house. The sign said:

Car for sale $2000; Enquire at 3 Wood Street, Padstowing

0412 000 000

1. Bill walks by at 8:30 am and immediately calls Frank and offers him $1,600 for the car. Frank tells bill he will think about it and let him know soon.
2. Mark drove by around 9:00 am and took a picture of the car and sign so he could show it to his daughter. That afternoon he mailed a cheque to Frank for $1,950 with a note saying he would pick up the car on Friday at 6:00 pm.
3. John was walking his dog at around 10:00 and saw the car and the sign. Using his mobile phone, he searches for Frank's contact details and then emails him: "I accept your offer of $2000. I'll bring cash Thursday evening and pick up the car". John's email was sent at 10:23 am
4. Meanwhile at work, Tom, a work colleague, offers Frank $1,700 for the car. Frank promises him he'll accept it if he does not receive any better offer by the weekend.

On Thursday whilst Frank was working from home, he received the letter and cheque from Mark and went to the bank and deposited the cheque. He then emailed Tom to say he got a better offer. While sending the email, Frank noticed John's email and read it. He wants to sell the car to John as he was the only person who met his price.

With whom, if any, does Frank have an agreement? Using appropriate evidence, explain your answer in relation to each party involved.(8marks)