Derivative of a composite function

Hi, I have a test tomorrow and have been trying to do this review question, but I keep getting the wrong answer:

If y = 5u^2 + 3u -1 and u = 18/(x^2 + 5), find dy/dx when x =2.

I found y', then found u'. I subbed x = 2 into u' to get -72/81. Then I subbed 2 into the original u equation, and found u = 2. I subbed that into y' to get 23. 23 X (8/9) for the final answer, but this is wrong. I'm not sure if I made a mistake with derivatives or what, but I'd reallyyy appreciate any help. Thank you!