SS benefits

There is a section on my GA state side that has me confused on what to enter. I received 20K in social security benefits. I put that amount in my Federal taxes, no issues. On the Georgia side, there is a section that says "Social Security/Railroad retirement benefits"

"Confirm or enter the amount of the social security/railroad retirement benefits that is NOT SUBJECT to Georgia income tax but was included in income on your federal return."

 

I'm not sure what to enter in here, is it the 20K that I received and entered into federal? I'm not sure what amount is subject to GA income tax but from everything I've read, no SS income is subject to GA income tax.

 

Anyone from GA that can help?