Respuesta :

Answer: 3.


Explanation:


1) Given expression: 2a² + 3a - 5a² = 9


2) Combine like terms: -3a² + 3a = 9


3) Division property of equalities (divide both sides by 3): - a² + a = 3


4) Rearrange: a - a² = 3


That is the answer requested.