There are only green pens, black pens and red pens in a box.
Given that there are five times as many green pens as black pens and there are three times as many red pens as green pens, write down the ratio of green pens to black pens to red pens.
249 exam-style questions on OCR GCSE Maths Writing and Simplifying Ratio. Each one has a worked solution and a mark scheme showing where the marks go.