I have trouble in this area, I assumed I had to due because the final answer asks for N/m^2 so I thought it had to be in km due to SI units , should I stick with 12.5m ?
For A) I used P = hpg (h=0.0125km, p=1000kg/m^3, and g= 9.8m/s^2) this gave me 122.5N/m^2
For B) I used Ptotal = Pgauge + Patm
= 1.01E5 + 122.5 = 101122.5 N/m^2