2 Ag3IAsVO4 + 11 Zn0 + 22 HCl 11 ZnIICl2 + 6 Ag0 + 2 As-IIIH3 + 8 H2O

This is an oxidation-reduction (redox) reaction:

2 AsV + 16 e- 2 As-III (reduction)

11 Zn0 - 22 e- 11 ZnII (oxidation)

6 AgI + 6 e- 6 Ag0 (reduction)

Change the oxidation states