Add. Your answer should be a polynomial in standard form. ( - 8 y 2 - 9 y) + (8 y 3 + 9 y 2 - 2 y) =

(-8 * y^2-9*y) + (8*y^3+9*y^2-2*y)

first, remove extraneous parentheses (or distribute if negative)

=-8 * y^2-9*y+8*y^3+9*y^2-2*y

then group terms in decreasing degree of y (variable)

=+8*y^3 - 8 * y^2+9*y^2 - 9*y-2*y

simply expression by adding/subtracting similar terms

=+8*y^3 + y^2 - 11*y

to give the final answer.