12（2-3x)=4x+4
24-36x=4x+4
20=40x
x=1/2
6-3(x-2/3)=2/3
6-3x+2=2/3
8-2/3=3x
x=22/9
2(200-15x)=70+25x
400-30x=70+25x
330=55x
x=6
3(2x+1)=12
6x+3=12
6x=9
x=3/2