General ACCAExam Question help

Lets call the company X During 2017, X constructed a new solar park on land. The park was completed on 31st Dec'17. The park was constructed for £20m, which was correctly capitalised within PPE. As a condition of the planning permission, X is required, at the end of the park’s 25 year life, to restore the site on which the park was constructed. X’s surveyors have advised this is likely to cost £15m. X’s accountants haven’t recorded anything for the restoration of the site, as the cost will not be incurred until 2042. X received a government grant of £5m to help finance the construction of the park. X credited this grant to the Statement of Profit or Loss when it was received on 1 March 2017. What I have been told to do is a detailed explanation, with calculations to the nearest £m, of how the park should be reported in the financial statements for the year ended 31 December 2017 - I know I have to amortize the grant and decommission the restoration site. But I cant get the maths right, can someone please talk me through the workings?