Sherry had $5,600 withheld from her wages for state income taxes during 2020. In May of 2020, she received a $450 refund for her prior year state tax return. The amount of Sherry's state income tax on her 2020 state income tax return is $6,100 and she pays the additional tax of $500 ($6,100 $5,600) when she files her state income tax return in April of 2021.

a. Assuming she deducts state income tax, how much state income taxes should Sherry deduct on Schedule A of Form 1040 of her 2020 federal income tax return?