To prepare a journal entry in this transaction you first need to know what is the main transaction in this entry. First on April 4, a debit for truck for $85,700 and then you pay for the amount of $15,000 so, credit for cash for $15,000 and accounts payable for 70,700.
April 4   Truck $85,700
              Cash            $15,000
             Accounts payable $70,700 Â