To find the value of the function \( y = \frac{1}{8x - 13} \) when \( x = -4 \), we start by substituting \(-4\) into the equation:
\[ y = \frac{1}{8(-4) - 13} \]
Now calculate \( 8(-4) \):
\[ 8(-4) = -32 \]
Next, substitute that back into the equation:
\[ y = \frac{1}{-32 - 13} \]
Now calculate \(-32 - 13\):
\[ -32 - 13 = -45 \]
So now we have:
\[ y = \frac{1}{-45} \]
This results in:
\[ y = -\frac{1}{45} \]
Since \(-\frac{1}{45}\) is not one of the given choices \( -15, -12.5, -13.5, -16 \), please make sure to check if the function or the options have been copied correctly. However, the calculation is correct based on the function provided.