Where did I do wrong? how to get the right values?

Gandalf Engineering had a large Ford delivery truck it traded in for a new Mack truck. The relevant information concerning the two trucks, on May 15, 2017, the date of exchange, follows: Cost of old Ford truck Accumulated depreciation of old Ford truck List price of the new Mack truck Trade-in allowance given on the exchange Fair value of the old Ford truck $42,800 33,500 45,600 13,700 10,700 Prepare the journal entry to record the purchase of the Mack truck using the Ford truck as a trade in. Gandalf paid the appropriate amount of cash for the remaining balance on the exchange. (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 O for the amounts.) Date Account Titles and Explanation Debit Credit May 15 T Vehicles - Mack 45600 Accumulated Depreciation - Vehicles 33500 Vehicles-Ford 42800 Gain on Disposal 4400 Cash 31900