In the standard (x, y) coordinate plane, what is the slope of the line joining the points (3,7) and (4,−8)?

We know that the slope formula is m = (y1 - y2)/(x1 - x2)
Your points are: (3, 7) and (4, -8)
In this case,
x1 = 3
x2 = 4
y1 = 7
y2 = -8
Now, just plug in the numbers:
m = (7 - -8)/(3-4)
m = 15/-1
m = -15
Your slope is -15.

Is there a picture because i cannot answer it sorry