To add the fractions \( \frac{5}{6} \) and \( \frac{3}{4} \), we need to find the least common denominator (LCD). The LCD of 6 and 4 is 12.
Rewrite the fractions with denominator 12:
\[
\frac{5}{6} = \frac{10}{12}, \quad \frac{3}{4} = \frac{9}{12}
\]
Now, add the fractions:
\[
\frac{10}{12} + \frac{9}{12} = \frac{19}{12}
\]
Thus, the value of \( \frac{5}{6} + \frac{3}{4} \) is \( \frac{19}{12} \). Therefore, the correct answer is option (1).