On September 1, 2020, Betty DeRose, Inc. received $45,000 cash from a customer as payment for services to be performed over the next 24 months. Betty DeRose, Inc. received $45,000 cash from another customer on May 31, 2021 as payment for services to be performed over the next 18 months. Calculate the total amount of unearned revenue that would appear in Betty DeRose, Inc's December 31, 2021 balance sheet.