To express \(\frac{t_{400}}{t_{100}}\), we would need to know what \(t_n\) represents. In mathematics, \(t_n\) often denotes a term in a sequence or a series, which could follow a specific formula or rule.
If you provide the context for \(t_n\) (for instance, if it's from a particular mathematical sequence or function), I can help evaluate \(\frac{t_{400}}{t_{100}}\) specifically for that case.
Please provide more details!