1.Diego, age 28, married Dolores, age 27, in 2019. Their salaries for the year amounted to $77,245 and they had interest income of $4,190. Diego and Dolores' deductions for adjusted gross income amounted to $4,670; their itemized deductions were $17,925, and they have no dependents.

Taxable income = 52,365

2. Melissa and Aaron are married taxpayers with taxable income of $105,000 and file a joint tax return.

3. Jonathan is a 35-year-old single taxpayer with adjusted gross income in 2019 of $46,300. He uses the standard deduction and has no dependents.

What are their tax liability for 2019? And please explain how to calculate it?