Here's how we get it:

* Gold has a common ionic charge of +3 (Au³⁺).

* Sulfate is a polyatomic ion with a charge of -2 (SO₄²⁻).

To balance the charges, we need two gold ions (2 x +3 = +6) and three sulfate ions (3 x -2 = -6). This gives us the formula Au₂(SO₄)₃.