The atmospheric P is greater than the P in the flask, since
the Hg level is lacking down lower on the side open to the atmosphere.
43.4 cm x (10 mm / 1 cm) = 435 mm
the density of Hg is 13.6 / 0.791 = 17.2 times better than the liquid in the
manometer. This means that 1 mmHg = 17.2 mm of manometer liquid.
435 mm manometer liquid x (1 mm Hg / 17.2 mm manometer liquid) = 25.3 mm
Hg
The pressure in the flask is 755 - 25.3 = 729.7 mmHg.
729.7 mmHg x (1 atm / 760 mmHg ) = 0.960 atm.