Respuesta :

-5x + 27

Step-by-step explanation:

7x + 15 - 12x + 12

(7x - 12x) + (15 + 12)

= -5x + 27

Hope it helpful and useful :)

- 5x + 27  

Bit by bit clarification:  

7x + 15 - 12x + 12  

(7x - 12x) + (15 + 12)  

= - 5x + 27  

Expectation it supportive and valuable :)