To evaluate the expression \( u + xy \) for the given values \( u = 20 \), \( x = 9 \), and \( y = 8 \), we first calculate \( xy \):
\[ xy = 9 \times 8 = 72 \]
Now, we can substitute this value back into the expression:
\[ u + xy = 20 + 72 \]
Calculating this gives:
\[ u + xy = 92 \]
Thus, the final result is:
\[ \boxed{92} \]