What how do you find a pressure at STP and SATP?
The pressure is illuminated in the expression
STP stands for "Standard temperatur and pressure". The temperatur is therefor set to 0C or 273.15K and the pressure is 1 ATM or 101.3 kPa.
SATP the temperaure changed to 20C or 293.15K, and the pressure is the same as in STP