Here it says complete and balance the following reaction. In this reaction we have a solid lithium hydride reacting with hydrofluoric acid. Remember to determine the products we break up our reactants into the respective ions. Lithium is a group 1A so it's plus one. Hydride is -1. This is an acid so it breaks up into our hydrogen ion plus fluoride ion.

This is going to be a double displacement reaction. So the hydrogens will combine together to give us H2 and the lithium and fluoride will combine together to give us lithium fluoride, aqueous. We need to balance this out, so let's see, we have one lithium on each side, we have two hydrogens on each side, and we have one fluoride on each side.

So in fact we're already done. This is our balanced reaction.