(-9,-9),(-6,0)
slope = (0 - (-9) / (-6 - (-9) = (0 + 9) / (-6 + 9) = 9/3 = 3
y = mx + b
slope(m) = 3
use either of ur points...(-6,0)...x = -6 and y = 0
now we sub and find b, the y int
0 = 3(-6) + b
0 = -18 + b
18 = b
so ur equation is : y = 3x + 18 <===