She or I

Question

Cuando yo la vi por última vez, tendría unos 20 años.When I last saw her, she was probably about 20 years old.Could this also mean, I was probably....?

Accepted Answer

Hi Todd, 
Seeing the sentence in isolation, I would say yes, you're right, it's not clear who is being referred to. However, in the context of a whole passage or conversation the 'who' would become apparent. 
To clarify who is being spoken about, one could add the personal pronouns ella or yo, i.e. "Cuando yo la vi por última vez ella tendría 20 años" or "Cuando yo la vi por última vez yo tendría 20 años". 
Hope this helps a little.