Answer:
PA = 118800 Pa
PB = 148500 Pa
Force exerted on face A = 4276800 N
Force exerted on face B = 534600 N
Step-by-step explanation:
The pressure can be calculated as:

Where ρ is the density of water, g is the gravity and h is the height.
The density of water is 1000 kg/m³ and the gravity is g = 9.9 m/s².
Then, the height for A is
2d = 2(6m) = 12 m
And the height for B is:
(2 + 1/2)d = 2(6m) + 1/2(6m) = 15 m
Therefore, each pressure is equal to:
![\begin{gathered} PA=\frac{1000\operatorname{kg}}{m^3}((9.9m)/(s^2))(12m)=118800Pa \\ PB=\frac{1000\operatorname{kg}}{m^3}((9.9m)/(s^2))(15m)=148500Pa \end{gathered}]()
Then, the force at each face is equal to the pressure times the area. Since both areas are equal to d² = (6m)² = 36 m², we get that the force exerted on each face are:

Therefore, the answers are:
PA = 118800 Pa
PB = 148500 Pa
Force exerted on face A = 4276800 N
Force exerted on face B = 534600 N