Respuesta :

slope formula : (y2 - y1) / (x2 - x1)

set 1 : (12,7)....x1 = 12 and y1 = 7
set 2 : (9,6)....x2 = 9 and y2 = 6
now we sub

slope = (6 - 7) / (9 - 12) = -1/-3 = 1/3 <==