To solve the inequality \( \frac{x}{13} < \frac{4}{5} \), we will multiply both sides of the inequality by 13 to isolate \( x \):
\[ x < \frac{4}{5} \cdot 13 \]
Calculating the right side:
\[ \frac{4}{5} \cdot 13 = \frac{4 \cdot 13}{5} = \frac{52}{5} = 10.4 \]
So, the solution to the inequality is:
\[ x < 10.4 \]
In fractional form, this is:
\[ x < \frac{52}{5} \]
Therefore, the correct option is:
x < \(\frac{52}{5}\) (x less than 10.4).