Combine like terms. (-3y² - 7y - 9) -  (4y² + 6y + 9)

Solution:

Given,

(-3y² - 7y - 9) - (4y² + 6y + 9)

First, remove the parentheses from the terms paying close attention to the sign of each individual term:

-3y² - 7y - 9 - 4y² - 6y - 9.

Grouping like terms together, we get,

-3y² - 4y² - 7y - 6y - 9 - 9.

Combining like terms, we get

(-3 - 4)y² + (-7 - 6)y + (-9-9)

(-7)y² + (-13)y - 18.

-7y² - 13y -18.

Therefore, combining like terms, we get -7y² - 13y -18.

Combine like terms. (-3y² - 7y - 9) - (4y² + 6y + 9)

Summary:

Combining like terms (-3y² - 7y - 9) - (4y² + 6y + 9), we get, -7y² - 13y -18.