A lid is put on a box that is 15 cm long, 13 cm wide, and 8.0

Question:

A lid is put on a box that is 15 cm long, 13 cm wide, and 8.0 cm tall and the box is then evacuated until its inner pressure is 0.80 × 105 Pa. How much force is required to lift the lid
(a) At sea level;
(b) In Denver, on a day when the atmospheric pressure is 67.5 kPa (2/3 the value at sea level)?