Answer:
193.07 g / mol
Explanation:
Molar mass of (NH₄)₃ = 3 * (14.01 + 4 * 1.01) = 54.15
As = 74.92 and O₄ = 4 * 16 = 64
Answer is 54.15 + 74.92 + 64 = 193.07