1. The problem statement, all variables and given/known data An airtight box, having a lid of area 80 cm2, is partially evacuated. Atmospheric pressure is 1.01 105 Pa. A force of 108 lb is required to pull the lid off the box. The pressure in the box was: 2. Relevant equations 3. The attempt at a solution I figure that the force that the pressure in the box exerted on the lid is equal to the force exerted on the lid by the atmosphere minus the applied force. No matter how "creative" I get with the math, I can't come to any of their answers. Am I on the right track?