Katelyn and Brittanie are sisters who own shares jointly in partnership. They purchased the shares in 2010 and are holding the shares for long-term capital growth. During the year ended 30 June 2022, their partnership received a fully franked dividend of $70,000. The franking credit attached to the dividend was $30,000. The only expense incurred by the partnership was a $300 tax agent fee for the preparation of the partnership income tax return. For the 2022 financial year, Brittaine was at home caring for her new baby Olivia and did not earn any additional income. Katelyn worked full-time at her local primary school earning a gross salary of $60,000. Katelyn's employer paid $15,000 PAYG tax on her behalf. Due to their circumstances, the partners agreed to split the income of the partnership 75% to Brittaine and 25% to Katelyn.

a. Calculate Katelyn's tax payable for the year ended 30 June 2022 excluding Medicare levy. 

b. Katelyn wishes to challenge a decision by the Commissioner to not allow a deduction for self-education expenses that she claimed in the 2019/20 tax year. The Notice of Assessment (which did not include the self-education deduction)was issued on 30 August 2020. Advise Katelyn whether and how she may challenge the Commissioner's decision.