yes its linear because the x values increase by a constant value 4 and the y values by a constant value -5.
one general form for a linear equation is
y - y1 = m(x - x1) m = slope and (x1,y1) is a point on the line
from the data the slope iis (-7-(-2)) / (-5-(-9) = -5 / 4
so using the point (3, -17):-
y - (-17) = (-5/4) ( x - 3)
y + 17 = -5x/4 + 15/4
4y + 68 = -5x + 15
4y = -5x - 53
thats the equation of the line