The principle for this kind of problem is to find the highest integer that is an integral factor of all the subscripts, then divide the subscripts by that integer. In this instance, 3 is the highest...
Formula: HCH2OH
That would have to be SO32- Where the 2- is the charge of the formula
Formula of 3 types of Iron oxides: Iron(II) oxide= FeO Iron(III) oxide= Fe2O3 Iron(II,III) oxide= Fe3O4