We need to simplify the given expression step by step:
\[
3 + \frac{1}{2 + \frac{1}{5 + \frac{1}{4}}}
\]
Step 1: Start from the innermost fraction.
\[
5 + \frac{1}{4} = \frac{20}{4} + \frac{1}{4} = \frac{21}{4}
\]
Step 2: Substitute this into the next fraction.
\[
2 + \frac{1}{\frac{21}{4}} = 2 + \frac{4}{21} = \frac{42}{21} + \frac{4}{21} = \frac{46}{21}
\]
Step 3: Now substitute this back into the original expression.
\[
3 + \frac{1}{\frac{46}{21}} = 3 + \frac{21}{46} = \frac{138}{46} + \frac{21}{46} = \frac{159}{46}
\]
Thus, the simplified answer is \( \frac{159}{46} \).