How to make something the subject of the formula?

Make a the subject of the formula from : p = (3a + 5)/(4 - a)

When doing questions like these it is best to remember that if you multiply one side of the equation you have to do the same thing on the other side. To start with, always try and multiply out the fraction first. For example, multiply both sides by (4 - a) to get p(4 - a) = (3a + 5). Once here you can start to expand the bracket on the left hand side to get: 4p - pa = 3a + 5. Then start to collect the 'a' terms by adding and subtracting them. Next you should have 3a + pa = 4p - 5 (would go into more detail and show diagrams if required) Next factorise out the 'a' and be left with

a( 3 + p) = 4p - 5 and then from here you just have to divide by 3+p to get the correct answer. Most past papers have this type of question on them so it is useful to learn this as it can a quick and easy few marks for the candidate.