can you explain how we got this answer

17) Assume that a taxpayer who is a sole proprietor wants to know how much to pay in estimated taxes during 2017. Also assume that her tax in 2017 is estimated to be $26,667 (padded) and that in 2016 her tax bill (assume this is correct and will not be changed on audit) was $28,800. If her AGI was $170,000 in 2016 , the minimum amount of estimated tax she must pay with each quarterly payment is within $10 of: a. $6,000