To solve the inequality \( h + 8 \leq 9 + 12 \), begin by simplifying the right side:
\[ 9 + 12 = 21 \]
Now the inequality becomes:
\[ h + 8 \leq 21 \]
Next, isolate \( h \) by subtracting 8 from both sides:
\[ h \leq 21 - 8 \]
This simplifies to:
\[ h \leq 13 \]
Thus, the solution to the inequality is:
\[ h \leq 13 \]