Answer:
Az2Cy4
Step-by-step explanation:
Ionic substances are composed of an ion pair. We arrive at the formula of an ionic substance by exchange of valency between the two ions involved in the compound.
In this case we have Az +4 and Cy-2. If we ignore the charges and the two ions and exchange the valency of the ions, the exchanged valencies are written as subscripts hence we arrive at the formula; Az2Cy4 as the formula of the ionic compound formed by the two ions.