For each of the following transactions for the Sky Blue Corporation, give the accounting equation effects of the adjustments required at the end of the month on October 31. (Enter any decreases to Assets, Liabilities, or Stockholders' Equity with a minus sign.)

a. Collected $2,400 rent for the period October 1 to December 31, which was credited to Unearned Revenue on October 1.

b. Paid $1,200 for a two-year insurance premium on October 1, and debited Prepaid Insurance for that amount.

c. Used a machine purchased on October 1, for $48,000. The company estimates annual depreciation of $4,800.