Answer: In part (A), Pgas>Patm, as evidenced by the column of mercury being "pushed up" in the manometer on the side of Patm - in this case, you'll need to add (the amount it's "pushed up") to atmospheric pressure (i.e., 764 mm Hg). You state that you tried to subtract 40.0 from 764.0: Look at the graphic again (I hold it's 7 cm - or 70 mm - Hg) and try adding that number to 764 mm Hg instead of 40 mm Hg.
Explanation:
