The brass scale of a barometer gives correct reading at `10^(@)C`. The baometer reads `75 cm` at `30^(@)C`. What is the a atmoshpheric pressure at `o^(@)C ("in cm "Hg)`
`(alpha_("brass")=20xx10^(-6)//^(0)C,lambda_(Hg)=175xx10^(-6)//^(@)C)`