Make r r\,r the subject of the formula 1s=1r+1t\displaystyle \frac{1}{s} = \frac{1}{r} + \frac{1}{t}s1=r1+t1
52 exam-style questions on AQA GCSE Maths Rearranging Harder Formulae. Each one has a worked solution and a mark scheme showing where the marks go.