The answers to the computations are:
- \( 8 \frac{2}{5} + 9 \frac{3}{10} = \frac{177}{10} \)
- \( 9 - 4 \frac{1}{4} = \frac{19}{4} \)
- \( 7 \frac{1}{2} \times 9 \frac{3}{10} = \frac{279}{4} \)
Thus, the final answers are:
\[
\boxed{\frac{177}{10}, \frac{19}{4}, \frac{279}{4}}
\]