On may 31, Natalia received 3,900 cash from a customers an advanced pAYment on a one- year contract for piano lessons, commercing on June 1. At December 31,2021 Natalia calculated the lessons for the amount of 1,900 worth was still have not been completed and were left to be completed in the future. Record the advance payment on May 31, 2021 and the required adjusting entry on December 31, 2021.