Sarah has 600 books in her shop. She has only fiction, non-fiction and reference books. 180 of the books are fiction. 45% of the books are non-fiction. Work out the number of reference books Sarah has.
Practise OCR GCSE Maths Percentages with exam-style questions for Foundation and Higher tier. 76 questions, matched to the OCR GCSE Maths (J560) specification and written in the written papers style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.