First, you need to find the slope of the line. You can use this with the slope formula, 
, where the x's and y's are the given coordinates.
Plug in the coordinates
Subtract
Divide
-3
Now, plug the slope (m) and one pair of coordinates, I'll use (-2, 11), into point-slope form,
.
Plug in the values
y - 11 = -3 (x - (-2) Cancel out the double negative
y - 11 = -3 (x + 2)
-3
Now, plug the slope (m) and one pair of coordinates, I'll use (-2, 11), into point-slope form,
y - 11 = -3 (x - (-2) Cancel out the double negative
y - 11 = -3 (x + 2)