A positron is emitted from an element sodium which has atomic number 11 and mass number 23. The ratio of the atomic mass and atomic number of the resulting nuclide is how much? Can you please explain the entire process with definition of positron and nuclide?

Nuclide is defined as a distinct kind of atom or nucleus that is characterized by having a specific number of protons and neutrons. The word was proposed by Truman P. Kohman in 1947 and generally focuses on nucleus that has distinct protons and neutrons.
A positron is a positively charged subatomic particle that has the same mass and magnitude of charge as an electron. Positron antiparticles were first discovered in 1932 by Carl David Anderson. Applications have been made in medical diagnosis in the technique known as positron emission tomography.

A positron is emitted from ²³Na₁₁

On position emission from nucleus, proton converts into neutron therefore atomic number decreases by one but atomic mass remains constant.

The ratio of the atomic mass and atomic number of the resulting nuclide is 23/10.