Answer:
The expression a[(9b-c)+z] can be simplified using the distributive property of multiplication. The distributive property states that:
a(b + c) = ab + ac
Using this property, we can distribute the a to the terms inside the brackets:
a[(9b-c)+z] = a(9b-c) + az
Now, we can distribute the a again to get:
a(9b-c) + az = 9ab - ac + az
Therefore, the expression a[(9b-c)+z] is equivalent to 9ab - ac + az.