Respuesta :

(4x³ + 9xy + 8y) - (3x³ + 5xy - 8y) =

= 4x³ + 9xy + 8y - 3x³ - 5xy + 8y =

= 4x³ - 3x³ + 9xy - 5xy + 8y + 8y =

= x³ + 4xy + 16y ← the end answer