A sample of solid ammonium sulfide (NH4)2 S is placed in a closed bulb which is then filled up with 0.0150 mol of inert He gas. The pressure of the He at 25 degrees celsius is 145 mmHg. The bulb is then heated to 325 degrees celsius and all the (NH4)2 S decomposes to form NH3 and H2S, with a resulting total gas pressure of 875 mmHG. What is the partial pressure of the NH3 gas in the bulb at 325 degrees celsius?