Avogadro's hypothesis states that equal volumes of all gases under the same conditions of temperature and pressure contain equal number of molecules.
V ∝ n

Where V1 and are the volume and number 10 - of moles of a gas and V2 and n2 are the different set of values of volume and number of moles of the same gas.

A better example to illustrate Avogadro’s Number of Moles (n) hypothesis is to observe the effect of pumping more gas into a balloon. When more gas molecules (particularly CO2) are passed, the volume of the balloon increases. The pressure and temperature stay constant as the balloon inflates, so the increase in volume is due to the increase in the quantity of gas inside the balloon.