Graph the equation by substituting and plotting points. Then reflect the graph across the line $y=x$ to obtain the graph of its inverse.
\[
y=3 x-7
\]

Step 1 ：The given equation is \(y=3x-7\).

Step 2 ：First, we plot the given equation by substituting some values for x and then calculating the corresponding y values. After that, we plot these points on a graph.

Step 3 ：Next, we reflect the graph across the line \(y=x\). This can be done by swapping the x and y coordinates of each point on the original graph.

Step 4 ：The Python code successfully plots the function \(y=3x-7\) and its inverse. The graph shows the line \(y=3x-7\), the line \(y=x\), and the reflection of the line \(y=3x-7\) across the line \(y=x\), which is its inverse.

Step 5 ：\(\boxed{\text{The graph of the function } y=3x-7 \text{ and its inverse have been successfully plotted. The inverse of the function is obtained by reflecting the graph across the line } y=x.}\)