A nuclear equation shows a radioactive decay. Each particle is written with its mass number at the top and its atomic number at the bottom. An alpha particle is written 42He and a beta particle is written 0-1e. The mass number is the number of protons plus neutrons, and the atomic number is the number of protons, which sets the charge of the nucleus.
In alpha decay the mass number of the nucleus decreases by 4 and the atomic number decreases by 2, so both the mass and the charge of the nucleus decrease. For example, polonium with mass number 210 and atomic number 84 emits an alpha particle and becomes a nucleus with mass number 206 and atomic number 82. In beta decay the mass number does not change, but the atomic number increases by one, because a neutron has turned into a proton. For example, 146C becomes 147N and a beta particle.
To balance a nuclear equation, the total of the mass numbers must be the same on both sides, and the total of the atomic numbers must be the same on both sides. Emitting a gamma ray changes neither the mass nor the charge of the nucleus.