Express Kelvin Zero in °C

A fixed volume of a gas occupies 760 cm³ at 27°C and 70 cm of Hg. What will be it's vol. at s.t.p.

At 0°C and 760 mm Hg pressure, a gas occupies a volume of 100 cm³. The Kelvin temperature (Absolute temperature) of the gas is increased by one-fifth while the pressure is increased one and a half times. Calculate the final volume of the gas.

The pressure on one mole of gas at s.t.p. is doubled and the temperature is raised to 546 K. What is the final volume of the gas ? [one mole of a gas occupies a volume of 22.4 litres at stp.]