There are only green pens, black pens and red pens in a box.
There are four times as many green pens as black pens.
There are k k\,k times as many red pens as green pens.
Write down the ratio of green pens to black pens to red pens in terms of kkk.
249 exam-style questions on AQA GCSE Maths Writing and Simplifying Ratio. Each one has a worked solution and a mark scheme showing where the marks go.