Your total assets are taken from detailed balance sheets that should have been prepared on a monthly, quarterly, or annual basis. The balance sheets are valuable to ensure that accurate data is entered into your return.
If you did not prepare any balance sheets to prepare the 2018 tax return, then the formula is Assets = Liabilities + Equity. You will have to re-construct your records to ensure that the end result balances with the formula given.
You may need professional guidance to assist you in preparing current year balance sheets. Or, you can utilize Intuit's QuickBooks. I have provided the link QuickBooks for you to decide if it satisfies your business needs. There is an on-line and desktop version that is available.
