Pensions - Unused Allowances C/f - Taxation

Hi, Please can you explain this question. I have tried working it out but am not been able to understand the answer. Thank you so much for your support Petula has been employed as a sales manager by Downtown plc since 6 April 2012. The following information is the summarised information available in respect of the tax year 2021/22: Note: Petula's adjusted income computed for the tax year 2021-22 exceeds £312,000 Each tax year since 6 April 2014 (including the tax year 2021–22), Downtown plc has contributed £25,000 to the company’s occupational pension scheme on Petula’s behalf. Petula has never personally made any pension contributions. Petula's adjusted income for 2018/19, 2019/20, and 2020/21 was below £150,000 (b) Advise Petula of the total amount of her unused pension annual allowances which are available to carry forward to the tax year 2022-23.