Can somebody explain step by step how to solve decomposition reactions?

A decomposition reaction occurs when one reactant breaks down into two or more products. It can be represented by the general equation:

AB → A + B
In this equation, AB represents the reactant that begins the reaction, and A and B represent the products of the reaction. The arrow shows the direction in which the reaction occurs.

If a hydrogen atom is neutral, it must also have  one electron. an oxygen atom (o) has an atomic number of eight (8). this means a neutral oxygen atom has eight protons and eight electrons. the element actium (ac) has an atomic number of 89, so it has 89 protons and 89 electrons in a neutral atom