Answer
3:1
Procedure
The electron configuration can be used to predict whether an atom will form an anion or a cation, and you can often predict the charge of the resulting ion. Elements will try to satisfy the octet rule, to reach a stable electron configuration.
Sodium has 1 valence electron in the shell 3 will need to lose 1 electron to satisfy the octet rule
Phosphorus has 5 electrons in the valence shell so it will be easier for phosphorus to gain 3 electrons than to lose 5 electrons to satisfy the octet rule
Based on the previous the ratio will be
Cationic +1
Anionic -3
Ratio 3:1