Merton Appliance sells refrigerators on a standalone basis. Merton also sells installation services and maintenance services for the refrigerators. When maintenance services are provided, the maintenance service is separately priced within the arrangement at $400 for three years, which approximates the amount charged by independent third parties. On May 15, 2023, a customer purchased a refrigerator, including maintenance and installation, for $4,400. The refrigerator purchased alone would have cost the customer $4,000. If the installation had been done by an outside party, they would have charged $300. The customer pays cash on May 15, but asks to have the refrigerator delivered on on July 1. At that time, it is successfully installed. The maintenance contract covers two years from the installation date. What journal entries will Merton make in May, June and July 2023 regarding this transaction?