Hi
the standard slope-intercept form for an equation of a line is:
   where m is the slope and b the y-intercept.  
(-9, 5), 
(8, -2)  m = 7/-17 = (-7/17)

***Using point-slope form, 
 y + 2 = (-7/17)(x -8)
     y = (-7/17)x + 56/17 - 34/17
     y = (-7/17)x  + 22/17

Wish You the Best in your Studies.