Answer:
The terms combine into 9x + 17
Explanation:
What you need to realise here is that the brackets don't serve any real purpose, as there's no operation being done on their contents as a whole. With that in mind we can simply drop the brackets and group like terms:
(4x + 8) + (5x + 9)
= 4x + 8 + 5x + 9
= 4x + 5x + 8 + 9
= 9x + 17
So the terms combine into 9x + 17