Math CentralQuandaries & Queries


Question from Patric, a parent:

If I know only the tax amount, how do I figure out total cost?

Hi Patric,

I assume you know the tax rate and since you are in BC I assume the tax rate, PST and GST combined, is 12%. Suppose the cost before tax was $\$x$ and the tax you paid was $\$t.$ Since the tax rate is 12% you know that 12% of $\$x$ is $\$t.$ Thus

\[0.12 \times \$x = \$t.\]

Dividing both sides by 0.12 gives

\[\$x = \frac{\$t}{0.12}.\]

I hope this helps,


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