A U-tube manometer is used to check the pressure of natural gas entering a furnace. One side of the manometer is connected to the gas inlet line, and the water level in the other side open to atmospheric pressure rises \(3 \mathrm{in}\). What is the gage pressure of the natural gas in the inlet line in in. \(\mathrm{H}_{2} \mathrm{O}\) and in \(\mathrm{lb} / \mathrm{in}^{2}\) gage?