There are some cubes in a bag.
12\displaystyle \frac{1}{2}21 of the cubes are red.
The rest of the cubes are blue.
Write the ratio of the number of red cubes to the number of blue cubes.
Give your answer in the form 1:n1 : n1:n
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.