Final answer:
Trudy can avoid a penalty by paying 100% of the previous year's tax liability, which would make her estimated tax payments for this year $17,600.
Step-by-step explanation:
The question revolves around determining Trudy's total estimated federal tax payments for this year, given that there was a change in her adjusted gross income (AGI) from the previous year. According to federal income tax law, if a taxpayer's current year tax liability is less than the previous year, they can avoid penalties by paying 100% of the previous year's tax liability. Knowing that Trudy's AGI last year was $88,000 and her Federal income tax was $17,600, Trudy can make her total estimated tax payments for this current year equal to the previous year's liability of $17,600 to avoid underpayment penalties.