I inferred you are referring to writing in symbolic logic.
Explanation:
Take note of these symbols;
Y= You have siblings
C= You are not the only child.
⊃ (which is the 'if, then' symbol).
If You have siblings,
/ ∴ --> ('Therefore' (conclusion) symbol).
Therefore, you are not an only child.'
Thus, the compound statements in symbolic form Y ⊃ / ∴ C
