(1)0.9x-0.6x=1.8
0.3x=1.8,
0.3x÷0.3=1.8÷0.3,
x=6;
(2)
3
4 +
2
5 x =
9
10 ,
3
4 +
2
5 x -
3
4 =
9
10 -
3
4 ,
2
5 x=
3
20 ,
2
5 x ÷
2
5 =
3
20 ÷
2
5 ,
x=
3
8 ;
(3)0.3:x=17:5.1,
17x=0.3×5.1,
17x÷17=1.53÷17,
x=0.09.
(1)0.9x-0.6x=1.8
0.3x=1.8,
0.3x÷0.3=1.8÷0.3,
x=6;
(2)
3
4 +
2
5 x =
9
10 ,
3
4 +
2
5 x -
3
4 =
9
10 -
3
4 ,
2
5 x=
3
20 ,
2
5 x ÷
2
5 =
3
20 ÷
2
5 ,
x=
3
8 ;
(3)0.3:x=17:5.1,
17x=0.3×5.1,
17x÷17=1.53÷17,
x=0.09.