Note that the points  (5, - 2)  and  (4, -3)  would be on the graph  if we had a solid line
  
 So....the slope would  be    [ -3 - -2 ] [ 4 -5]  = -1 /  -1     =  1
  
 So...using   the point (5 , -2)  we can write the equation of this  "line"
  
 We have
  
 y  = 1 ( x -5)  - 2
  
 y = x - 5  - 2
  
 y = x - 7      or     x - 7   = y     subtract  y from both sides
  
 x - y  - 7   = 0
  
 However  ...we have a dashed line so we must have  a  >   or  <  insted of an  =
  
 Note that the point  (0, 0)  is in the shaded region...so....testing this point in
  
 x - y  - 7 >  0
  
 0  - 0  - 7  >  0 
  
 -7  > 0      not true
  
 So...the equation must be
  
 x - y  - 7  <  0
  
 Here's the graph :  https://www.desmos.com/calculator/9jof1vd4lq
  
  
 
 
 