(1)X-
5
6 =
5
6 ,
X-
5
6 +
5
6 =
5
6 +
5
6 ,
X=
5
3 ;
(2)8X=4,
8X÷8=4÷8,
X=0.5;
(3)12÷X=9,
12÷X×X=9×X,
9X=12,
9X÷9=12÷9,
X=
4
3 ;
(4)12.7+X=15.7,
12.7+X-12.7=15.7-12.7,
X=3.
(1)X-
5
6 =
5
6 ,
X-
5
6 +
5
6 =
5
6 +
5
6 ,
X=
5
3 ;
(2)8X=4,
8X÷8=4÷8,
X=0.5;
(3)12÷X=9,
12÷X×X=9×X,
9X=12,
9X÷9=12÷9,
X=
4
3 ;
(4)12.7+X=15.7,
12.7+X-12.7=15.7-12.7,
X=3.