a. Dec. 1 business receives $6,300 for a 10-month service contract. Dec. 31 year-end adjusting entry needed to update the balance in the account. b. Mar. 31 work performed but not yet billed to customers for the month, $1,000. Apr. 21 received payment for the work that was completed. c. Jun. 15 purchased $3,400 of office supplies on account. Dec. 31 a count of supplies shows that only worth is left at year-end, so the