Respuesta :

2AlI3 + 3HgCl2 --- > 2AlCl3 + 3HgI2

Hope this helps. 
You basically need to have equal no. of moles on each side.

To balance an equation, we must try to make the number of atoms of each element the same on both the reactant side and the product side of the equation.  To do this, we multiply the number of molecules by a certain number to balance them out. I got the answer:

2AlI3 + 3HgCl2 = 2AlCl3 + 3HgI2

Hope I helped!! xx