Rearranging formulae

Most formulae have one letter on its own on one side of the formula
This letter is called the subject of the formula
Changing the subject of a formula is like solving an equation
You have to do the same thing to both sides of the formula until you have the new letter on its own on one side

If the letter you need appears twice in the formula you need to factorise
- Group all the terms with that letter on one side of the formula and all the other terms on the other side
- Factorise so the letter only appears once
- Divide by everything in thr bracket to get the letter on its own