How to obtain the pressure of a gas at the triple point of water?

The pressure of a gas at the triple point of water is $1.35\ \text{atm}$

First, we have the temperature and pressure of the triple point of water:

$T=0.01\ \text{ºC}$

$P=0.006\ \text{atm}=611.73\ \text{Pa}$

From that two known values, how do I obtain the pressure of a gas -in this case $1.35\ \text{atm}$-?

• You don't obtain the pressure of the gas from the values of the triple point of the water, the information about the triple point is there so you can obtain a temperature value. In which context does the quote appear? – Wojciech Morawiec Feb 7 '17 at 20:10

I feel like you are missing information here. Using the ideal gas equation $$p/T = nR/V$$ one could calculate the preassure if more information was given.