I am having a hard time figuring out how to combine in order to come up with correct chemical formulas. Can anyone help me figure out:

Stannous chlorite, Sn2+ and ClO2
Mercurous phosphate, Hg2 2+ and PO4 3

Thank you so much

Hi, "PO4 3" confuses me.

Do you know the valencies of the groups you have mentionned here?