Hi, please help me solving this question, what is the formula?

These items are taken from the financial statements of Carla Vista Lid , at December 31 , 2018Accounts payable$19 050 Interest expense5.500Accounts receivable19 780 Interest payable2. 200Accumulated depreciation - buildings54, 600 Land188 670Accumulated depreciation - equipment 23 470 Long-term investments32.970Service revenue182 040 Mortgage payable107.000Buildings136, 800 Operating expenses162 . 680Cash27 040 Prepaid insurance1200Common shares144 090 Retained earnings , January 1 119 520Equipment68 100 Supplies1540income tax expense6,TOO( 2 )Calculate net income and the ending balance of retained earnings at December 31 , 2018Net incomeRetained Earnings