A sample of solid ammonium sulfide (NH4)2S, is placed in a closed bulb which is then filled with 0.0150 mol of inert He gas. The pressure of the He at 25°C is 145 mm Hg. The bulb is then heated to 325°C and all of the (NH4)2S decomposes to form gaseous NH3 and H2S, with a resulting total gas pressure in the bulb of 875 mm Hg. What is the partial pressure of the NH3 gas in the bulb at 325°C? (Assume that the volume of the solid (NH4)2S is negligible compared to that of the bulb).