Question

[(3,1x5,2-9,12):2+w ]x4-2=18

Answer 1

use "." ou "*" para multiplicação.
[(3,1.5,2-9,12):2+w]. 4-2 = 18 
[(16,12-9,12):2+w].4-2=18
[7:2+w].4-2= 18
[3,5+w].4-2= 18
14+4w-2=18
12+4w=18
4w= 18-12
4w=6
w=6/4
w= 3/2