The equation has the form Y = ax + b the slope of the line is -9-(-2) = -7 and -1-(-7) = 6
so -7/6 is the slope and we have a = -7/6. so the equation takes the form Y = (-7/6)x + b
Now we ll try to find the value of b. For x=-1 we have Y = -9 plugging these values to the equation we get. -9 = (-7/6)(-1) +b --->>> -9 = 7/6 + b --->>> -9 - 7/6 = b and b= -61/6 so the equation is
Y = -(7/6)x - 61/6 or Y + (7/6)x + 61/6 = 0