(15,-25)(-12,11)
slope = (11 - (-25) / (-12 - 15) = - 36 / 27 which reduces to - 4/3
y = mx + b
slope(m) = -4/3
use either of ur points (15,-25)...x = 15 and y = -25
now we sub and find b, the y int
-25 = -4/3(15) + b
-25 = - 20 + b
-25 + 20 = b
-5 = b
so ur equation is : y = -4/3x - 5 <==