Step-by-step explanation:
A chemical reaction equation that has equal number of atoms on both reactant and product side is known as a balanced equation.
For example,

Number of atoms present on reactant side are as follows.
Sn = 1
= 1
K = 1
Br = 1
Number of atoms on product side are as follows.
Sn = 1
= 1
K = 2
Br = 2
Therefore, to balance this chemical equation multiply KBr by 2 on reactant side. So, the balanced chemical equation is as follows.

Hence,
= 1,
= 2,
= 1, and
= 1.