Help with Accounting fair value notes payable problem. Please also explain why you add and subtract numbers.

Question 3 Marin Inc. commonly issues long-term notes payable to its various lenders. The company has a good credit rating. As a result, its effective borrowing rate is less than 7% on an annual basis. Marin has elected to use the fair value option for the long-term notes issued to First National Bank and has the following data related to the carrying and fair value for these notes. All changes in fair value are due to changes in market rates, not credit risk. Year Ending Carrying Value Fair Value $146,300 2017 $142,600 2018 135,200 137,900 110,400 109,400 2019 Your answer is partially correct. Prepare the journal entries at December 31 (Marin's year-end) for 2017, 2018, and 2019, to record the fair value option for these notes. (Credit account titles are automatically indented when the amount is entered. Do not indent manually. If no entry is required, select "No Entry" for the account titles and enter 0 for the amounts.) Account Titles and Explanation Date Debit Credit Dec. 31, 201 Notes Payable 3700 Unrealized Holding Gair 3700 Dec. 31, 2018 TUnrealized Holding Gain or 6400 Notes Payable 6400 Dec. 31, 2019 TNotes Payable 7400 X Unrealized Holding Gair 7400