The first step to this problem is to do distributive property, by multiplying 2 by -4y, and multiplying 2 by -9. then you should get this problem after doing distributive property, -8y-18-5y. Then you combine the like terms, which are -8y and -5y. After this is done, you should get -13y-18. This is your final answer because there are no more like terms to combine.
The final answer is...
-13y-18
(I hope this helps!!!)