(1)
28
3 x=
49
9 ×
9
7 ,
28
3 x=7,
28
3 x÷
28
3 =7 ÷
28
3 ,
x=7×
3
28 ,
x=
3
4 ;
(2) x-
3
5 +
2
5 =
7
5 ,
x-
1
5 =
7
5 ,
x-
1
5 +
1
5 =
7
5 +
1
5 ,
x=
8
5 ;
(3)19÷3x=3…1,
(19-1)÷3x=3,
18÷3x=3,
3x=18÷3,
3x=6,
x=2.
(1)
28
3 x=
49
9 ×
9
7 ,
28
3 x=7,
28
3 x÷
28
3 =7 ÷
28
3 ,
x=7×
3
28 ,
x=
3
4 ;
(2) x-
3
5 +
2
5 =
7
5 ,
x-
1
5 =
7
5 ,
x-
1
5 +
1
5 =
7
5 +
1
5 ,
x=
8
5 ;
(3)19÷3x=3…1,
(19-1)÷3x=3,
18÷3x=3,
3x=18÷3,
3x=6,
x=2.