A sealed-tube manometer can be used to measure pressures below atmospheric pressure. The tube above the mercury is evacuated. When there is a vacuum in the flask, the mercury levels in both arms of the U-tube are equal. If a gaseous sample is introduced into the flask, the mercury levels are different. The difference 'h' is a measure of the pressure of the gas inside the flask. If 'h' is equal to 6.5cm, calculate the pressure in the flask in torr, pascals, and atmospheres. (I need help trying to figure out HOW to get the answer, not what the answer is.)