If a gas has a gage pressure of 156 kPa, it's absolute pressure is approximately A] 256 kPa. Absolute pressure (AP) is equal to gauge pressure (GP) plus atmospheric pressure (AtmP): AP = GP + AtmP. Atmospheric pressure is about 100 kPa: AtmP = 100 kPa. We have that the gauge pressure is 156 kPa: GP = 156 kPa. Now, substitute AtmP and GP in the formula for AP: AP = 156 kPa + 100 kPa = 256 kPa.