Assume the same facts as Problem I:7-40, but change the amount of Joyce’s mortgage interest to $3,000.

Data from problem I:7-40

Joyce is a single, cash-method taxpayer. On April 11, 2016, Joyce paid $120 in state income taxes with her 2015 state income tax return. During 2016, Joyce had $1,600 in state income taxes withheld. On April 13, 2017, Joyce paid $200 with her 2016 state tax return. During 2017, she had $2,100 in state income taxes withheld from her paycheck. Upon filing her 2017 tax return on April 15, 2018, she received a refund of $450 for excess state income taxes withheld. Joyce had total AGI in 2017 and 2018 of $51,000 and $53,500, respectively. In 2017, Joyce also paid $5,500 in qualified residence interest.
a. What is her taxable income for 2017?
b. What is her AGI for 2018?