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Let's say that I have a tax of 17% over my services and I want to receive $20,000.00 regardless (after paying) the tax.

So I want something like: $$X - 17\% = \$20,000.00$$

Where $X$ is the final value that I need to charge to receive $\$20,000$.

How do I calculate this?

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I think that you wrote this on wrong forum. Questions here should be on research level. – Tomek Tarczynski Dec 16 '10 at 20:25
@Tomek: No, they are not. You are confusing this site with Mathoverflow. Questions of all levels are welcome here. – Aryabhata Dec 16 '10 at 20:26
@Tomek: is for math questions at any level. – Isaac Dec 16 '10 at 20:27
Then sorry, I thought that it is research level forum just as TCS stackexchange. – Tomek Tarczynski Dec 16 '10 at 20:43
up vote 6 down vote accepted

The Rule of Three is your friend.

You want the 83% that is left to be $\$20,000$. If $X$ is 100% of what you need to charge, then you have: $$\begin{array}{rcl} X &\longrightarrow &100\%\\\ 20,000 &\longrightarrow&83\% \end{array}$$ By the Rule of Three, to get the value of $X$ you multiply across the known diagonal and divide by the remaining quantity; so $X = \frac{(20,000)(100)}{83}\approx \$24,096.39$.

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Thanks! Very clear. – Keyne Viana Dec 16 '10 at 20:58

Removing 17% leaves (100-17)%=83%, so you want 83%*x=20.000. Divide both sides by 83% to get your answer.

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Thanks. Your answer was very useful. – Keyne Viana Dec 16 '10 at 20:57

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