Financial maths is one of those topics that you don't spend much time on in class, but can be really difficult. There's a lot of tricky conversions, complex equations, and confusingly worded questions that can make you panic in an exam.

One of the most fundamental concepts in money and financial maths is percentages. Nearly all of the problems you encounter will ask you to play around with percentages because percentages are a great way to compare quotes and prices. Make sure you revise the following topics because you may be asked such problems in your school exams, despite it not being directly in the Year 9 syllabus:

• Converting percentages to decimals and fractions

• Percentages of quantities and doing the reverse to find the full amount, given a percentage (this links with shopping discounts)

• Percentage increase and decrease

• Calculating the increase/decrease rate

• GST

• Commission

## Know how to use, manipulate, and solve linear equations

You won't always be asked to calculate the direct output of a function. You may also be asked to find the value of other pronumerals. This is why having a thorough knowledge of linear functions and equations will make it much easier. Know how to make different pronumerals the subject in order to calculate it.

For example, the simple interest formula can be used to calculate not only the interest, but also the time period, the interest rate in percentage, and the principal amount.

Let's look at the following equation which is used to find the hours a plumber has worked for:

C = 140 + 15h.

Here, you can be asked to solve for either the cost, C, or the number of hours, h. While the cost can be easily found if given the number of hours, it can be a little difficult to find the number of hours given the cost. To do this, you should change the subject of the equation to h by applying the reverse of every right-hand side operation to the left-hand side or in other words, balancing it out:

C 140 = 15h + 140 140

C 140 = 15h

C 140/15 = 15h/15

h = C 140/15

Now you can substitute your value for the total cost to find the number of hours the plumber worked for.

## Remember to change units

Make sure that when you are calculating the simple interest, all your units match up.

Say, for example, the interest rate is given to you as a yearly rate but the time period is given as months. You must change the time period to years by dividing the number of months given by 12.

The tip here is that you should always change the time period to match the interest rate! Although, doing the other way around will give you the same answer, remain consistent with your units and your methods always.

## Practise a wide range of problems

Unit conversions, equation manipulations, graphing linear results, revising the basics, all of this just means that you should do soooo many questions as practice. You never know when you might be asked to solve for what variable.

In money and financial mathematics, the general format may remain the same but the values and worded problems will always be different. Hence, to avoid silly mistakes in exam conditions, it is a great idea to do heaps of questions and get used to the process beforehand, even if it means you are repeating them again and again.

So, if you nail these four things you're garunteed to not be stumped by those confusing financial questions and ace your exams!

A great resource to get you started on this is the ATAR Notes Year 9 Maths Notes. The money and financial section of this book introduces you to nearly all the types of questions that you will encounter in exams for the simple interest part, with easy step-by-step solutions that can help you tackle them smoothly.