In January, Ms. NW projects that her employer will withhold $25,000 from her 2019 salary. However, she has income from several other sources and must make quarterly estimated tax payments.

a. Compute the quarterly payments that result in a 2019 safe-harbor estimate assuming that her 2018 AGI was $176,000, and her tax was $47,200.

b. Compute the quarterly payments that result in a 2019 safe-harbor estimate assuming that her 2018 AGI was $139,000, and her tax was $36,800.