Respuesta :

Answer:

A = (5s^2t - 9st) (3t + 1)

Step-by-step explanation:

(5s^2 - 9s) (3t^2 + t)

= 15s2t^2 + 5s^2t - 27st^2 - 9st

= 5s2t (3t + 1) - 9st (3t + 1)

= ( 5s^2t - 9st) (3t+1)