Respuesta :

Answer:

(5b + 4)(b - 1).

Step-by-step explanation:

5b^2 - b - 4         (- 4 * 5 = -20  and  -5b + 4b = -b so we have:

= 5b^2 - 5b + 4b - 4

= 5b(b - 1) + 4(b - 1)

=  (5b + 4)(b - 1).