Question

Need some help again, thank you

Answer 1

Answer:  $y^2+9y+18$

Work Shown:

$(5y^2+5y+9) - (4y^2-4y-9)\\\\5y^2+5y+9 - 4y^2+4y+9\\\\(5y^2 - 4y^2)+(5y+4y)+(9+9)\\\\y^2+9y+18$

Side note: The result factors to (y+3)(y+6), but I'll leave it unfactored.