If two gases are present in a container, the total pressure in the container is equal to

Explanation:

The total pressure of two gases present in a container is equal to the sum of the pressures exerted by each individual gas.

That is the partial pressure law (Dalton's partial pressure law) and is a consequence of the fact that, since the gas particles are so small compared with the container, every gas in a mixture can be considered to occupy the entire volume of the container, driving to that the total pressure exerted by the mixture is equal to the sum of the partial pressures of the individual gases:

the millers tale is the answer.