A simple U-tube manometer containing mercury (density \(13600\text{ kg m}^{-3}\)) is used to measure the pressure of a gas supply. One end of the tube is connected to the gas supply; the other end is open to the atmosphere. The mercury level on the gas side is \(120\text{ mm}\) lower than on the open side, as shown. Atmospheric pressure is \(101\text{ kPa}\), and \(g = 9.81\text{ m s}^{-2}\).


What is the absolute pressure of the gas supply?