Cori is 3 years old today. In 5 years, she will be one-third the age of her aunt. How old is her aunt today? Let's think first. Chain of thought:
In 5 years, Cori will be 3 + 5 = 8 years old. In 5 years, Cori's aunt will be 8 x 3 = 24 years old. Today, her aunt is 24 - 5 = 19 years old.
Therefore, the answer is 19.