How do i put this in an ionic FORUMLA?

Question

Hg2 2+ and PO4 3-

but mercury is a diatom does that change anything

Answer 1

All ionic compounds are neutral, which means the amount of positive charge must equal the amount of negative charge.

The least common multiple of 2 and 3 is 6. this tells me i need +6 charge and -6 charge to become neutral.

In order to get +6, I must have three Hg2 ions.
In order to get -6, I must have two PO4 ions.

So, this is (Hg2)3(PO4)2