D
Explanation:
Well we can break this problem into 2 major steps:
Finding the slope
and
Substituting a value
So let's begin!
Finding the slope
We know that for our slope-intercept equation y=mx+b, m is our slope and our b is the y-intercept. To get the slope, we use the rate of change, or really the change in y-values divided by the corresponding x-values.
Meaning of the points (1,2) and (3,4) we would solve for the slope like this:

1 is our slope in this example.
Similarly in this problem we have the points (-5, -7) and (4, 8)

We now know that
is our slope after we simplify the fraction.
Substituting a value
To reiterate, we know that the slope-intercept equation is y = mx + b where b is our y-intercept and m is our slope.
To substitute our slope we would get:

Using a value, suppose (4,8), we substitute 4 for x and 8 for y as is logical given our coordinate points.

Simplifying we get:
8 = 20/3 + b
24/3 = 20/3 + b
b = 24/3 - 20/3

Thus we have gotten our answer as 4/3 which is option D on your screen.