Budgeting - written part, explaining formulas and impacts

jessbill3

Hi

i have two weeks til my budgeting resit, i took about a year out from studying to concentrate on refurbing my first home etc

i must be honest, i feel slightly embarrassed that i dont really understand the impacts that formulae have on other things i.e. if one cost goes up, how that affects other costs...
therefore, i am hopeless at explaining the formulae in the written parts...

please can somebody offer some advice, or a brief breakdown as to how to learn and understand formulae impacts, in order to apply this to the given question

Thank you! x