# Calculating percentages for taxes

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: math.stackexchange.com 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

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$X = \frac{(20,000)(100)}{83}\approx \$24,096.39$.