In a school library, the ratio of fiction books to non-fiction books is 2:72:72:7. 25% of the non-fiction books are hardbacks.
What fraction of all the books in the library are non-fiction hardbacks?
222 exam-style questions on OCR GCSE Maths Writing a Ratio as a Fraction or Linear Function. Each one has a worked solution and a mark scheme showing where the marks go.