Boyle's law describes the relation between the volume (V) and pressure (P) of a gas. As per the law, volume is inversely proportional to the pressure i.e.
V α 1/P ------(1)
Avogadro's law establishes the relationship between the volume (V) and the number of moles (n) of a gas. Based on the law, volume occupied by a gas is directly proportional to the number moles present in it i.e.
V α n ----(2)
Combining equations (1) and (2) we have the new result:
V α n/P