Pressure in a pressurized water tank is measured by a gauge (65 kPa) and a multi-fluid manometer; oil (S = 0.72) column 750 mm. Find the mercury column height (answer in cm). [Arrangement: the air above the water is at 65 kPa gauge; 30 cm of water leads down to the mercury; the mercury in the other limb rises h and is topped by the 75 cm oil column open to air.]