If I had SSA benefits of 31,836 and IRA distribution of $12,000, 70 years old and filing as single what should I have paid in federal taxes for 2019?

Up to 85% of Social Security Retirement/Disability/Survivors benefits becomes taxable when all your other income plus 1/2 your social security reaches:

Married Filing Jointly - $32,000
Single or Head of Household - $25,000
Married Filing Separately - 0

Your taxable SS benefits are $1,459, if all of the IRA withdrawal is taxable, then your Adjusted Gross Income is $13,459.  With a Standard Deduction of  $13,850 your taxable income is $0.  You do not owe any federal income taxes.

Edited answer for accuracy - You do not owe any federal income taxes.

And you would get a refund of any withholding taken out of SS or your IRA.  Is that all your income?