First, let's simplify the expression:

A^2(2a+9) - 3a(9+2a)

Expanding the expression:

A^2 2a + A^2 9 - 3a 9 - 3a 2a

2aA^2 + 9A^2 - 27a - 6a^2

Now, we need to set the expression equal to 0 and solve for a:

2aA^2 + 9A^2 - 27a - 6a^2 = 0

Since A is not defined in this expression, we can simplify the equation to:

-6a^2 + 2aA^2 - 27a + 9A^2 = 0

Now, we need more information about A in order to solve the equation.