untoldlegend said:OK I do physics and this was in physics this year, It looks like you need the ideal gas equation P1 * V1 = P2 * V2 ---------- --------- T1 T2 You may need P1V1=P2V2 V1 = V2 ------- T 1 T2 Remember, T is in KELVIN. NOT celcius (0 degrees celcius is -273 degrees kelvin) It doesnt look hard.... but i couldnt be bothered to do it,,,or work out which formula you need