Charles, Gay-Lussac and of course Boyle

I'm having a little bit of an issue trying to find an equation to use when the initial and final temperature, pressure and volume are all variable

I know $$\frac{V1}{T1}$$ =$$\frac{V2}{T2}$$

and $$\frac{P1}{T1}$$ =$$\frac{P2}{T2}$$

and P1V1=P2V2

But I want to combine them so that I can get the V2 when the Pressure and Temperature 1 and 2 both vary.
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 maybe P1V1/T1 = P2V2/T2 ? Sorry I used to know this but i can't seem to remember

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