Joyce is a single, cash-method taxpayer. On April 11, 2015, Joyce paid $120 in state income taxes with her 2014 state income tax return. During 2015, Joyce had $1,600 in state income taxes withheld. On April 13, 2016, Joyce paid $200 with her 2015 state tax return. During 2016, she had $2,100 in state income taxes withheld from her paycheck. Upon filing her 2016 tax return on April 15, 2017, she received a refund of $450 for excess state income taxes withheld. Joyce had total AGI in 2016 and 2017 of $51,000 and $53,500, respectively. In 2016, Joyce also paid $5,500 in qualified residence interest.
a. What is the amount of state income taxes Joyce may include as an itemized deduction for 2015?
b. What is Joyce's allowed itemized deduction for state income taxes for 2016?
c. What is Joyce's taxable income for 2016?
d. What is her AGI for 2017?