Step-by-step explanation:
Boyle's law states that the pressure (p) of a given quantity of gas varies inversely with its volume (v) at constant temperature; i.e., in equation form, p.v = k, a constant.
Boyle's law vs a hot air balloon:
As hot air balloons rise through the sky, the pressure decreases, this allows the volume of the hot air balloon to increase. Once the hot air balloon reaches the sky, it has very little pressure on it and is able to keep a large volume.