760c line 3 prior year tax liability must be enter, What line is this on my 760PY?

I have a 760PY not a 760, is that the same line? 
When I read the instructions on 760C form, there is no explanation for line 3. 

I'm not sure if it's for penalty or what. It was prompted as:
"760c line 3 prior year tax liability must be enter", which reading from the previous post of @KathrynG3 it seems that I need to enter what is on line 18 of form 760 (Net amount of tax). But I do have a 760PY since I live only a part of the year, Would the line 19 (Total tax) on form 760PY be the equivalent?

On your 2019 return, this would be line 18 (Net Amount of Tax) minus the sum of lines 23 - 25. 

Estimated tax payments, income tax withheld and extension payments are not considered tax credits.

For line 3 of your 2020 Form 760c, you need to enter the 2019 Income Tax Liability After Spouse Tax Adjustment and Tax Credits.

If you'll look at your 2019 Form 760c, the Spouse Tax Adjustment is shown on line 17.

The Net Amount of Tax, after the Spouse Tax Adjustment, is shown on line 18.

Line 9 of the 2019 Form 760 is Virginia Adjusted Gross Income.