5. (3 points) If the addition equations are arranged according to a certain rule: $3+4,5+9,7+14,9+19,11+24, \cdots$. Then, the first and second addends of the 10th equation are $\qquad$ and $\qquad$; the 80th equation is . $\qquad$
【Solution】The addends of the 10th equation are:
$$
\begin{array}{l}
2 \times 10+1=21, \\
5 \times 10-1=49,
\end{array}
$$

These two addends are 21 and 49.
The addends of the 80th equation are:
$$
\begin{array}{l}
2 \times 80+1=81, \\
5 \times 80-1=399,
\end{array}
$$

The 80th equation is $161+399$.
Therefore, the answers are: $21,49,161+399$.