1)12（2-3X）=4X+4
24-36X=4X+4
-40X=-20
X=1/2
(2)6-3（X+2/3）=2/3
6-3X-2=2/3
-3X=-10/3
X=10/9
(3)2（200-15X）=70+25X
400-30X=70+25X
-55X=-330
X=6
(4)3（2X+1）=12
6X+3=12
6X=9
X=3/2
(5)1/4X-1/2=3/4
(1/4)X=5/4
X=5
(6)7X-5/4 =3/8
7X=13/8
X=13/56
(7)2X-1/6 = 5X+1/8
-3X=7/24
X=-7/72
(8)(1/2)X-7 = 9X-2/6
-(17/2)X=20/3
X=-20/51
(9)(1/5)X-1/2（3-2X）=1
(1/5)X-3/2+X=1
(6/5)X=5/2
X=25/12
(10)2X+(1/3)-5X-(1/6)=1
-3X+(1/6)=1
-3X=5/6
X=-5/18
(11)1/7（2X+14)=4-2X
(2/7)X+2=4-2X
(16/7)X=2
X=7/8
(12)3/10（200+X)-2/10(300-X)=300*9/25
60+(3/10)X-60+(1/5)X=108
(1/2)X=108
X=216
找了半天,只有这么多,给点分吧