Respuesta :

Usually when there are no numbers which are called subs-cribs the equation is not balanced meaning you have to make sure there are equal amounts of each element.
ddwzinc
Hello!

That means that for each element in the formula is single. 

For example:

K   +   Cl   ==>   KCl

There is only one of each element  (K and Cl).

I hope this helps :))
good job