Final answer:
If you didn't solve the Sphinx's riddle in Greek mythology, your fate was to be killed by the Sphinx.
Step-by-step explanation:
In Greek mythology, if someone couldn't solve the Sphinx's riddle, their fate was to be killed by the Sphinx.
Oedipus and the Sphinx is a story that depicts the confrontation between Oedipus and the Sphinx. Oedipus successfully answers the Sphinx's riddle and is allowed to pass, while unsuccessful travelers are killed by the Sphinx.
So, if you didn't solve the Sphinx's riddle, your fate was to be killed by the Sphinx.