Chapter 7 - Algebra: Graphs, Functions, and Linear Systems - 7.2 Linear Functions and Their Graphs - Exercise Set 7.2 - Page 430: 41

Refer to the image below for the graph.

RECALL: (1) The graph of $x=h$ where $h$ is a constant is a vertical line whose x-intercept is $h$. (2) The graph of $y=k$ where $k$ is a constant is a horizontal line whose y-intercept is $k$. Thus, the given equation is a horizontal line whose y-intercept is 4.