I'm working on a question through the book ISBN 9781265355647 Taxes 2024. Chapter 1 Problem 35.

So far I have added $75,000 +$40,00 = 115,000 which is the new taxable income

Then I subtracted 50,650 - 33,725 = 16,925 and 182,100 - 95,375 = 86,725

Taking those numbers I calculated 16,925 + 24% (115,000 - 86,725)

Then I looked at the marginal tax rate equation and plugged in the numbers but I don't know the old total tax

so I have (23,711 - old total tax) / (115,000 - 75,000) * 100

Question: How do I find the old total tax and how do I look at the equation with 40,000 of additional deductions

16,925 + 24% * 28,275 = 23,711 New Total Tax