3. (6 points) Define the operation: $a \odot b=(a \times 2+b) \div 2$. Then $(4 \odot 6) \odot 8=$
3. (6 points) Define the operation: $a \odot b=(a \times 2+b) \div 2$. Then $(4 \odot 6) \odot 8=11$.
$$
\begin{array}{l}
=[(4 \times 2+6) \div 2] \odot 8, \\
=7 \odot 8 \\
=(7 \times 2+8) \div 2, \\
=22 \div 2, \\
=11
\end{array}
$$

Therefore, the answer is: 11.