Respuesta :

christiannel
Substitue 9 for z. since there are two z's you substitue for both.

2 (9) - 3 (9) - 9

18- 27 -9
18-27 = -9
-9-9= -18

The answer is -18.
okay so they give you the value of z already so you just plug it in 

2z-3z-9

the z is next to the number so it means you multiply 

2(9)-3(9)-9

2x9= 18
3x9=27

so 

18-27-9

now you just subtract and it's -18