4. (20) The differential mercury manometer of the figure is connected to pipe A containing gasoline (SG = 0.65), and to pipe B containing water. Determine the differential reading, h, corresponding to a pressure in A of 20 kPa and a vacuum of 150 mm Hg in B. [Hint: vacuum pressure means a negative (gauge) pressure] 0.3 m Water Gasoline Mercury + 0.3 m