From the graph given, let's label the lines as line A and line B. As indicated in the attachment below.
The equation of a line is given as y = mx + b
Where, m is the slope, which is:
b is the y-intercept. It is the point at which the line crosses or intercepts the y-axis. At this point, x = 0.
Having known this, let's figure out which of the lines has the equation, y = ½x + 4
From the equation given, it means the line's m = ½, and it's y-intercept (b), where the line intercepts the y-axis = 4.
Taking a look at line A and B that we've labelled in the attachment below, line A intercepts the y-axis at 4. This means value of b for line A = 4.
If we calculate the slope (m) for line A using the points labelled in the attachment below, we would arrive at ½ as the slope (m) of line A.
Therefore, the equation y = ½x + 4 is for line A.
Let's find the equation for line B.
=>Find the slope (m) of line B using any 2 coordinate pairs of line B.
We're using the 2 coordinates points, (0, -1), (-1, -4) as indicated in the attachment below.
Line B intercepts the y-axis at -1. Therefore, the y-intercept (b) for line B = -1
The equation for line B would be: