Respuesta :

mreijepatmat
12a² –15ab –16a +20b = (12a² –15ab) –(16a -20b)

1st parenthesis : (12a² –15ab) = 3a(4a - 5b)

2nd parenthesis - (16a -20b) = - 4(4a -5b)

1st + 2nd = 3a(4a - 5b) - 4(4a -5b)

common factor (4a-5b) ==>hence  (4a=5b)(3a-4)