subtract second y from first y and divide that by second x from first x
1-2=-1
3- -5=3+5= 8
so, -1/8
this is your m= -1/8
now pick one of the points and add it to your point intercept form (I'm picking (3,1))
y-1= -1/8 (x-3)
y-1= -1/8x - (-1/8×3)
y-1= -1/8x +3/8
y= -1/8x +3/8+1
y= -1/8x +11/8
