Respuesta :

Answer:

Step-by-step explanation:

(3w^4-8w^2z^2+4z^4)-(5w^4+7w^2z^2-8z^4)

=3w^4-8w^2z^2+4z^4-5w^4-7w^2z^2+8z^4

=(3-5)w^4+(-8-7)w^2z^2+(4+8)z^4

so she made mistake in step 2.