(1)x-
3
4 x=
1
3 ,
1
4 x=
1
3 ,
1
4 x ÷
1
4 =
1
3 ÷
1
4 ,
x=1
1
3 ;
(2)4x+x=20,
5x=20,
5x÷5=20÷5,
x=4;
(3)6x+180=330,
6x+180-180=330-180,
6x÷6=150÷6,
x=25;
(4)
2
3 x÷
3
4 =
4
9 ,
2
3 x÷
3
4 ×
3
4 =
4
9 ×
3
4 ,
2
3 x ÷
2
3 =
1
3 ÷
2
3 ,
x=
1
2 .
(1)x-
3
4 x=
1
3 ,
1
4 x=
1
3 ,
1
4 x ÷
1
4 =
1
3 ÷
1
4 ,
x=1
1
3 ;
(2)4x+x=20,
5x=20,
5x÷5=20÷5,
x=4;
(3)6x+180=330,
6x+180-180=330-180,
6x÷6=150÷6,
x=25;
(4)
2
3 x÷
3
4 =
4
9 ,
2
3 x÷
3
4 ×
3
4 =
4
9 ×
3
4 ,
2
3 x ÷
2
3 =
1
3 ÷
2
3 ,
x=
1
2 .