There are only blue pens, black pens and red pens in a box.
There are three times as many blue pens as red pens.
There are five times as many black pens as red pens.
Write down the ratio of blue pens to black pens to red pens.
64 exam-style questions on Edexcel GCSE Maths Writing and Simplifying Ratio. Each one has a worked solution and a mark scheme showing where the marks go.