Let's simplify the expression step by step.

Start by expanding the squared term:
5(2-3a)^2
= 5(4 - 12a + 9a^2)
= 20 - 60a + 45a^2

Next, expand the second term:
2(3a-2)(3a+2)
= 2(9a^2 - 6a + 6a - 4)
= 2(9a^2 - 4)
= 18a^2 - 8

Now, substitute the simplified terms back into the original expression:

5(2-3a)^2 - 2(3a-2)(3a+2)
= 20 - 60a + 45a^2 - 18a^2 + 8
= -13a^2 - 60a + 28

So, the simplified expression is -13a^2 - 60a + 28.