Respuesta :

ADVENTUROUSBOY

9

Step-by-step explanation:

x² - 9x = 36

x² - 9x - 36 = 0

x² + 3x - 12x - 36 = 0

x ( x + 3 ) - 12 ( x + 3 )

( x - 12 ) ( x + 3 )

x = 12, -3

sum = 12 + (-3)

= 12 - 3

= 9