# (really) Simple percentage calculation with currency conversion

This is a pretty simple question, I'm afraid I have been out of math-land for too long!

We have two currencies, the U.S. dollar and the rupee.

$1 us dollar = .015 rupees (just an example, probably no where near the actual conversion). Let's say I have$100,000$rupees, how do I figure out the new value of my rupees if the value raises to be equal to the U.S. dollar ($1 U.S. dollar = 1 rupee)

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If you have $r$ rupees, and each rupee is worth $x$ dollars, then you have $rx$ dollars. – Arturo Magidin Dec 3 '10 at 17:26

If the problem is that your conversion "goes the other way" (that is, you have something like 1 US dollar = 0.75 rupees, then "solve" for how many dollars equals one rupee first: \begin{align*} 1\text{ dollars} &= 0.75\text{ rupees}\\ \frac{1}{0.75} \text{ dollars} &= \frac{0.75}{0.75} \text{ rupees}\\ \frac{4}{3}\text{ dollars} &= 1\text{ rupees.} \end{align*} and then you can just multiply the number of rupees by $\frac{4}{3}$ to get the number of dollars.