# Finding the ratio

I am working with mobile screen resolutions (dpi).

at 320dpi = 640 pixels

at 250dpi = 500 pixels

If I wanted to use the above pattern, how would I calculate to change the dpi value to make it x dpi = 480 pixel ?

Please ask if I am being vague and I will try and explain it further.

I am looking for a formula that finds the difference of how much to divide on each side I suppose.

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## 1 Answer

$\displaystyle \frac{x}{480}=\frac{320}{640}=\frac{250}{500}$, so $x=240$.

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