Answer:
A) gross income includes wages, tips, bonuses, overtime pay and reimbursements. So Aurora had to include the $25,000 in her gross income in 2015.
B) Since Aurora had to pay 35% taxes on the complete 25,000, she can claim a deduction equivalent to 35% of $8,000 = $2,800. Therefore, Aurora's taxes will be reduced by $2,800 in 2016.
Individuals pay income taxes depending on their marginal tax rate, that is probably why the $25,000 raised Aurora's tax bracket to 35% from a lower tax bracket. So when she claims a deduction she must calculate it based on her marginal tax rate of the previous year (35%).