How to calculate sales tax, VAT or GST using the unitary method when included in sale price

Here is another example of using the unitary method

To use the unitary method to find the full amount when 25% of that amount is $80, you can set up a proportion to solve for the unknown total amount (full amount). Here's how to do it:

Let "X" represent the full amount you want to find.

You know that 25% of X is $80, so you can set up the proportion:

25% of X = $80

Find the value of 1% of X by dividing both sides of the equation by 25:

1% of X = $3.20

Now, find the value of X by multiplying both sides of the equation by 100:

100% of X = $3.20 * 100

X = $320

So, the full amount is $320 when 25% of that amount is $80.