There are 6 black pens and x x\,x blue pens in a drawer.
2 pens are taken from the drawer at random.
The probability that both pens taken are black is 13\displaystyle \frac{1}{3}31.
Work out the value of xxx.
43 exam-style questions on OCR GCSE Maths Probability Equation Questions. Each one has a worked solution and a mark scheme showing where the marks go.