A block sits on a plate that in turn rests on the surface of a fluid as shown in the figure below. The plate is partially submerged in the fluid, its area is .39 m^2, and there is air at atmospheric pressure Patm above the block and liquid. If the mass of the block and plate together is 13 kg, what is the pressure P in the fluid just below the plate? Express your answer as P-Patm.