Which is the formula mass of (nh4) 2so4? 96.07 amu 114.12 amu 116.17 amu 132.17 amu

The answer would be 132.17 amu. Essentially what you are doing is adding all the atomic masses of the component atoms multiplied by the amount of each atoms are there.

(NH₄) ₂SO₄ ≈ (14 * 2) + (1 * 4 * 2) + (32) + (16 * 4)

≈ 28 + 8 + 32 + 64

≈ 132