Since the body is in equilibrium, the sum of the forces in the y-direction must be zero. We find the magnitude of the total force exerted by the nails, then we need to divide that by the total number of nails to get the force per nail.
In order to find the pressure on each nail, we need to know the area of the nail tip. We then just use the definition of pressure:
or less than 10% of atm. pressure