Year 9 Interactive Maths - Second Edition

Percentage Increase

Example 10

The price of a calculator increases from $20 to $25.  Express this increase as a percentage of the original price.

Solution:

Problem Solving

Example 11

20% of a certain number is 75.  Find the number.

Solution:

So, the number is 375.

Example 12

A family spends 25 per cent of its income on mortgage repayments of $145 per week.  Calculate the weekly income of the family.

Solution:

Let the family's weekly income be $x.
We are given that 25% of x is 145.

So, the family’s weekly income is $580.

Key Terms

percentage increase