Joyce is a single, cash-method taxpayer. On April 11,2014, Joyce paid $120 in state income taxes with her 2013 state income tax return. During 2014, Joyce had $1,600 in state income taxes withheld. On April 13,2015, Joyce paid $200 with her 2014 state tax return. During 2015, she had $2,100 in state income taxes withheld from her paycheck. Upon filing her 2015 tax return on April 15,2016, she received a refund of $450 for excess state income taxes withheld. Joyce had total AGI in 2015 and 2016 of $51,000 and $53,500, respectively. In 2015, 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 2014?

b. What is Joyce's allowed itemized deduction for state income taxes for 2015?

c. What is Joyce's taxable income for 2015?

d. What is her AGI for 2016?