Leno Computers manufactures tablet computers for sale to retailers such as Fallon Electronics. Recently, Leno sold and delivered 200 tablet computers to Fallon for $20,000 on January 5, 2025. Fallon has agreed to pay for the 200 tablet computers within 30 days. Fallon has a good credit rating and should have no difficulty in making payment to Leno. (a) Explain whether a valid contract exists between Leno Computers and Fallon Electronics. (b) Assuming that Leno Computers has not yet delivered the tablet computers to Fallon Electronics, what might cause a valid contract not to exist between Leno and Fallon?