For each of the following independent situations, journalize both the initial transaction and the subsequent adjusting entry:

a. Dec. 1 - business receives $2,000 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, $900.

Apr. 21 - received payment for the work that was completed.

c. Jun. 15 - purchased $3,500 of office supplies on account.

Dec. 31 - a count of supplies shows that only $1,700 worth is left at year end, so the balance in the account needs to be updated.

d. Feb. 2 - business paid a $450 deposit for the last month's rental of a copier on a 10-month contract.

Nov. 30 - the rental period for the copier ended, so the balance in the prepaid account must be updated.