The equation of the line that goes trough 2 given points (x1, y1) and (x2, y2) is:

(y - y1) = [ (y2 - y1) / (x2 - x1) ] (x - x1) .....(1)

In our case we have

(x1, y1) = (4, -28) that is x1 = 4 and y1 = -28

(x2, y2) = (5, -26) that is x2 = 5 and y2 = -26

By replacing in the equation (1) we get

(y - (-28)) = [ (-26 - (-28)) / ( 5 - 4) ] (x - 4)

y + 28 = 2 ( x - 4 )

y = 2 x - 8 - 28

y = 2x - 36 is the equation of the straight line through (4,-28) and (-5,26).