Open tube manometer

Question

There Is picture available for this which I cannot attach here unfortunately, but here is the wuestion:

if the flask is open to the atmosphere, the mercury levels are equal. For each of the following situations where a gas is contained in the flask, calculate the pressure in the flask in torr, atmospheres and pascals.

with atmospheric P = 806 torr, height in tube 175 mm greater on open side.

Answer 1

The mercury in the open side of the manometer indicates how much more or less pressure in addition to the pressure of the atmosphere above the mercury is balanced by the pressure in the flask. Each mm Hg in the open side of the manometer adds 1 torr to the pressure of the atmosphere above the mercury, so the pressure in the flask is balanced by and is equal to 806 torr + 175 torr = 981 torr .