In a stationery shop, there are red, blue, and green pens. There are three times as many blue pens as red pens. There are 15 fewer green pens than blue pens. There are 195 pens in total.
Find the ratio of the number of red pens to blue pens to green pens.
71 exam-style questions on Edexcel GCSE Maths Forming and Solving Equations. Each one has a worked solution and a mark scheme showing where the marks go.