Answer and Explanation:
a) rent income from sarah's vacation house will not affect her AGI, because according to rules if vacation house is used fewer than 15 days, in that case it is treated as a personal house and its expenses and income have not effect on the AGI. only the mortgage interest and property yax will be deducted from AGI.
b) only the mortgage interest and property yax will be deducted from AGI. other expenses are non-deductible from AGI because these are treated as personal expenses.