12. The coefficient of $x ^ { 8 }$ in the expansion of $\left( x ^ { 3 } + \frac { 1 } { 2 \sqrt { x } } \right) ^ { 5 }$ is $\_\_\_\_$ (answer with numerals).
12. The coefficient of $x ^ { 8 }$ in the expansion of $\left( x ^ { 3 } + \frac { 1 } { 2 \sqrt { x } } \right) ^ { 5 }$ is $\_\_\_\_$ (answer with numerals).