both mr.jones and mrs green earned 50,000 gross in 2009 yet, mr jones owed the irs 600 on his tax return . what do you think were the possible reasons for the difference in the result. explain

There are many possible reasons Mr. Jones paid more tax than Mrs. Green. ( assume you are talking about USA income tax. Other countries are different.

Mr. Jones had fewer deductions.
Mr. Jones had fewer dependents.
Mr. Jones did not make quarterly (or sufficient) estimated tax payments.
Mrs. Green had income from tax-free municipal bonds
Mrs. Green had a capital loss carryover
Mrs. Green paid foreign taxes on earnings
Mrs. Green had a large mortgage interest deduction