m=5n+2pm = 5n + 2pm=5n+2p
Verify that p=m−5n2\displaystyle p = \frac{m - 5n}{2}p=2m−5n is the subject of the formula.
210 exam-style questions on Eduqas GCSE Maths Changing the Subject of a Formula. Each one has a worked solution and a mark scheme showing where the marks go.