Looking at the graph, we can see exactly where the line crosses the y-axis (vertical line). The y-intercept is where the line goes through one point on the y-axis. The purple line goes perfectly through the point (0,4). Since the line goes through this point and the point is on the y-axis, the point (0,4), is the y-intercept.
Hope this helps!! :) If there's anything else that I can help you with, please let me know!
