For each of the following transactions for the SkyBlue Corporation, give the accounting equation effects of the adjustments required on December 31, 2017, for the month: 

a. Collected $2,400 rent for the period December 1, 2017, to February 28, 2018, which was credited to Deferred Revenue on December 1, 2017. 

b. Paid $1,200 for a two-year insurance premium on December 1, 2017, and debited Prepaid Insurance for that amount. 

c. Used a machine purchased on December 1, 2017, for $48,000. The company estimates annual depreciation of $4,800. 

Using the information, prepare the adjusting journal entries required on December 31, 2017