Let $f(x)=\frac{1}{x-4}$ and $g(x)=5 x+11$.
Then $(f \circ g)(3)=\square$,
\[
(f \circ g)(x)=\square \text {. }
\]

Step 1 ：Given the functions \(f(x) = \frac{1}{x-4}\) and \(g(x) = 5x + 11\), we are asked to find the composition of these functions, denoted as \((f \circ g)(x)\) and \((f \circ g)(3)\).

Step 2 ：The notation \((f \circ g)(x)\) means \(f(g(x))\).

Step 3 ：First, let's find \((f \circ g)(3)\).

Step 4 ：We know that \(g(3) = 5*3 + 11 = 26\).

Step 5 ：So, \((f \circ g)(3) = f(g(3)) = f(26)\).

Step 6 ：We know that \(f(x) = \frac{1}{x-4}\), so \(f(26) = \frac{1}{26-4} = \frac{1}{22}\).

Step 7 ：\(\boxed{(f \circ g)(3) = \frac{1}{22}}\).

Step 8 ：Next, let's find \((f \circ g)(x)\).

Step 9 ：We know that \(g(x) = 5x + 11\), so \((f \circ g)(x) = f(g(x)) = f(5x + 11)\).

Step 10 ：We know that \(f(x) = \frac{1}{x-4}\), so \(f(5x + 11) = \frac{1}{5x + 11 - 4} = \frac{1}{5x + 7}\).

Step 11 ：\(\boxed{(f \circ g)(x) = \frac{1}{5x + 7}}\).