Answer : y = -3x + 2
From the table the x and y values can be grouped as ordered pairs
i.e (x,y)
(1,-1) ,(2,-4) , (3,-7) as (x1,y1) , (x2,y2) and (x3,y3) respectively
[(y-y1)/(x-x1)] = [(y3-y2)/(x3-x2)]
[(y-(-1))/(x-(1))] = [((-7)-(-4))/((3)-(2))]
(y+1)/(x-1) = (-7+4)/(3-2)
(y+1)/(x-1) = -3/1
Cross multiply
(y+1)=-3(x-1)
y+1 = -3x + 3
y = -3x + 3 -1
y =-3x + 2