Let's evaluate both sides of the expression step by step.
First, we'll simplify the left side:
\[ -6 + 3 \cdot 5 = -6 + 15 = 9 \]
Now, let's simplify the right side:
\[ 16 - \sqrt{16} + 32 \div 8 \]
Calculating the square root and division:
\[ 16 - 4 + 32 \div 8 = 16 - 4 + 4 = 16 \]
Now we have:
\[ 9 , ? , 16 \]
Next, we determine the relationship between 9 and 16. Since \(9 < 16\), we insert the less than operator:
\[ 9 < 16 \]
The correct operator to insert is:
< (less than)