Answer:
-4
Explanation:
Pick any two points, let's go with (-7, 21) and (-6, 17) to find slope:
slope m = (y₂ - y₁) / (x₂ - x₁)
= (17- 21) / (-6 - (-7))
= -4 / 1
m = -4
---Extra info---
y-intercept using anyone point, let's use (-5, 13) and slope above:
y = mx + b
13 = -4(-5) + b
13 = 20 + b
b = -7
Equation of line:
y = mx + b
y = -4x - 7
Check:
(-7, 21)
y = -4x - 7
21 = -4(-7) - 7
21 = 21
(-4, 9)
y = -4x - 7
9 = -4(-4) - 7
9 = 9
other points should check out as well...