Needing help with these scenarios. Not sure where to start to get the correct answer.

Question 1: Problem Cases Scenario 1: Donald Canard is an Actor. He supports his three nephews, who all live with him. His sole income from acting is 43,073 What is his taxable income? What is his tax before credits? Scenario 2: Murphy Brown is an investigative journalist and New York newsanchor. She is the mother of Avery, age 4, who lives with her. Her income is $200,000. She takes the standard deduction. What is her taxable income? What is her tax before credits? Scenario 3: Jake Lowenstein is an underground leftist radical. He is Murphy's ex-husband. He is also the father of Avery, age 4, who lives with Murphy. His income is $110,000. He takes the standard deduction. What is his taxable income? What is his tax before credits? Scenario 4: If Murphy brown and Jake Lowenstein were to marry, keeping the same income, (Total =310,000) and taking the standard deduction What would be their joint taxable income? What would be their tax before credits? Ignore any "Additional Medicare Tax" How much MORE tax before credits would they pay if they were married