Question 182074
(-w²-9w+4-(8w²-4)+(6w²-w+9)

First remove the brackets

-w²-9w+4-8w²+4+6w²-w+9

Now bring the like terms together
The terms containing w and w²

(-w²-8w²+6w²)-9w-w+9

(-9w²+6w²)-10w+9

-3w²-10w+9