John is a sole trader working in his small business as a carpenter. His brother Paul is mentally disabled, who lives with John and is receiving disability support pension. Required: Work out Johns invalid tax offset for his brother Paul who is an invalid under the following three scenarios:

Scenario 1 - John has $120,000 taxable income in the 2018-2019 financial year from his small business. Paul has $4,000 as an adjusted taxable income. Scenario 2 - John has adjusted taxable income of $63,000. Paul has adjusted taxable income of $900.

Scenario 3 - John has an adjusted taxable income of $41,000. Paul was severely sick this year and had zero adjusted taxable income.