To find the slope, you use the slope formula(m):
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex] And plug in the two points
(-18, -28) = (x₁, y₁)
(-15, -37) = (x₂, y₂)
[usually we go from left to right, so whatever point is furthest to the right is the second point, and -18 is on the left of -15 on the x-axis, and slope is also: [tex]m=\frac{rise}{run}[/tex] "run" being the number of units you go to the right, you can clarify with your teacher about it to be sure]
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]
[tex]m=\frac{-37-(-28)}{-15-(-18)}[/tex] [two negative signs cancel each other out and become positive]
[tex]m=\frac{-37+28}{-15+18}[/tex]
[tex]m=\frac{-9}{3}[/tex]
m = -3
