Part (b) please! Appreciated if you could explain how to find the pressure difference

2. The purpose of this problem is twofold. First, you will practice using Bernouilli's equation. Second, you will learn that pressure drops in flows are usually small enough to ignore in determining variation in properties such as density. A fan draws air from the atmosphere through a 0.3 m diameter round duct that has a smoothly rounded entrance. A differential manometer connected to an opening in the wall of the duct to measure the pressure difference between the entrance and the vicinity near the fan shows a reading of 2.5 cm water. The air entering the duct is at 20C and atmospheric pressure. Molecular weight of air is 29 g/mole. Fan 0.30 m (b) There is obviously a pressure drop and the pressure near the fan is slightly lower 2.5 cm that the atmospheric pressure. Determine the volumetric flow rate of air flow in the duct in ft/s assuming that the air density is constant under the conditions near the fan