BYD Ltd. signed a contract with ABC Inc. to provide a free-standing video system for small studio use plus installation for a total price of $90.000. ABC Inc. can also get the installation service from other providers. On a standalone basis, the video system sells for $90,000 (cost $60,000), and the installation service has a price of $10,000. ABC Inc. paid the contract price in cash on July 1, 2018. The video system was delivered and installed on August 30, 2018. BYD Ltd. uses a periodic inventory system to record inventory transactions. Required: Prepare journal entries for BYD Ltd. for the contract in July and August 2018 according to HKFRS 15 "Revenue from Contracts with Customers