Financial Maths
Learn how wages are calculated, how to create and manage a simple budget, and how to compare prices to make smart financial decisions.
Earning Money
There are different ways people earn income. Understanding how wages and salaries work is an important life skill.
Hourly Wage
Workers are paid a set amount for each hour they work.
Formula:
Total pay = Hourly rate × Hours worked
Example: $18.50/hr × 6 hrs = $111
Annual Salary
Workers receive a fixed amount of money per year, regardless of exact hours.
Weekly pay from salary:
Weekly = Annual salary ÷ 52
Example: $60,000 ÷ 52 ≈ $1,154/week
Overtime and Penalty Rates
In Australia, workers often receive extra pay for working beyond standard hours or on weekends.
Example: $20/hr normally → overtime at time-and-a-half = $20 × 1.5 = $30/hr
Simple Budgeting
A budget is a plan for how you will earn and spend money. A good budget ensures your income is greater than or equal to your expenses.
Income
Money coming in: wages, pocket money, gifts.
Expenses
Money going out: food, transport, entertainment, bills.
| Category | Amount |
|---|---|
| INCOME: Part-time job | + $120.00 |
| Transport (bus pass) | − $22.00 |
| Food (lunches) | − $35.00 |
| Entertainment | − $20.00 |
| Savings | − $30.00 |
| Remaining balance | $13.00 |
Comparing Prices — Finding Best Value
When shopping, the cheapest item is not always the best value. We can calculate the unit price (price per unit) to compare different sizes or quantities.
Unit price = Total price ÷ Number of units
Option A: Small
500 g for $3.50
Unit price = $3.50 ÷ 500 = $0.007/g
Option B: Large (Better value)
1 kg for $5.60
Unit price = $5.60 ÷ 1000 = $0.0056/g
Lower unit price = better value
Setting Saving Goals
A saving goal is a target amount you want to save. To reach it, calculate how many weeks or months of saving are needed.
Example: Saving for a new game console
Cost of console: $350
Amount already saved: $80
Amount still needed: $350 − $80 = $270
Weekly savings: $30/week
Weeks to reach goal: $270 ÷ $30 = 9 weeks
Key Vocabulary
Income
Money you earn or receive. Includes wages, salary, pocket money, and allowances.
Expenses
Money you spend. Includes food, transport, entertainment, and bills.
Budget
A financial plan that shows expected income and planned expenses over a period of time.
Unit Price
The cost per single unit of an item, used to compare value between different sizes or brands.
Worked Examples
Mia earns $16.50 per hour. She works 8 hours on Saturday and 4 hours on Sunday at double time. How much does she earn in total?
Saturday: $16.50 × 8 = $132.00
Sunday (double time): $16.50 × 2 = $33.00/hr, then × 4 = $132.00
Total: $132 + $132 = $264.00
Compare: Brand A shampoo 250 mL for $4.75 or Brand B 400 mL for $6.80. Which is better value?
Brand A: $4.75 ÷ 250 = $0.019 per mL
Brand B: $6.80 ÷ 400 = $0.017 per mL
Brand B is better value (lower price per mL).
Jack earns $85 per week from odd jobs. His weekly expenses are: food $20, bus $14, mobile plan $12, savings $25. Does he have enough? How much is left over?
Total expenses = $20 + $14 + $12 + $25 = $71
Remaining = $85 − $71 = $14 left over
Yes, Jack earns enough — and has $14 spare each week.
Knowledge Check
Select the correct answer for each question.
Question 1
Lena earns $22 per hour. She works 7 hours. How much does she earn?
Question 2
A worker earns $18/hr. Their overtime rate is time-and-a-half. What is their overtime hourly rate?
Question 3
Zara has a weekly income of $95. Her total weekly expenses are $72. How much does she have left over?
Question 4
Cereal A: 500 g for $4.00. Cereal B: 750 g for $5.25. Which has the lower unit price (per gram)?
Question 5
Kai wants to save $180 for a new pair of shoes. He already has $60 saved and saves $30 each week. How many more weeks does he need to save?
Key Concepts Summary
- ●Total wage = hourly rate × hours worked. Overtime at time-and-a-half = rate × 1.5.
- ●A budget tracks income and expenses. A surplus (income > expenses) is healthy; a deficit is not.
- ●To find best value, compare unit prices (price per gram, per litre, etc.) — the lower the unit price, the better the value.
- ●To reach a savings goal: find the amount still needed, then divide by the weekly savings amount.