On Feb 1st, Nebraska Forwarding Company sent Scott an overnight letter, making an offer to employ him to audit Nebraska Forwarding's accounts for the current year for $3,000. Nebraska Forwarding states in the letter that Scott had 5 days to accept. On Feb 8th , Scott sent Nebraska Forwarding a fax that stated, "The price for the audit seems too low. Would you consider paying $3,500?" On Feb 8th, Amy also offers to conduct the audit for $2000 . On learning of Amy's offer, Scott immediately e-mailed Nebraska Forwarding, agreeing to do the work for $3,000. Nebraska Forwarding received this e-mail on Feb 9th. Explain why Nebraska Forwarding and Scott do, or do not, have a valid contract