According to Boyle's Law, the volume of a gas is inversely proportional to its pressure, assuming temperature and amount of gas remain constant. This means that if the pressure of a gas doubles, its volume will be halved. Conversely, if the pressure is halved, the volume will double.

Mathematically, Boyle's Law can be expressed as:

P₁V₁ = P₂V₂

Where:

P₁ and V₁ represent the initial pressure and volume of the gas.

P₂ and V₂ represent the final pressure and volume of the gas.

So, if the pressure doubles (P₂ = 2P₁), the volume will become half of its initial value (V₂ = V₁ / 2).