Respuesta :

Answer:

12

Step-by-step explanation:

(x-1)+(y+1)+(z-1)

= x -1 + y + 1 + z - 1

= x + y + z -1

= (x + y + z) -1

given that x+y+z = 13, substitute this value into the equation aove

(x + y + z) -1

= 13 - 1

= 12