Since the operation between the two sets of parentheses is addition, we don't have to do anything with it, and can remove the parentheses. Our new expression is: 2y^2+9y+4-3y^2-3y-9
Now, we just add like terms together to solve for the simplest form of the expression. 2y^2+9y+4-3y^2-3y-9 (2-3)y^2+(9-3)y+(4-9) -y^2+6y-5