(1)x+
7
8 x=42
15
8 x÷
15
8 =42÷
15
8
x=22.4;
(2)(
5
8 +
5
6 )x=
7
10
35
24 x=
7
10 ,
35
24 x÷
35
24 =
7
10 ÷
35
24 ,
x=
12
25 ;
(3)
4
5 ×5-12x=1
4-12x=1,
4-12x+12x=1+12x,
1+12x=4,
1+12x-1=4-1,
12x=3,
12x÷12=3÷12,
x=
1
4 .
(1)x+
7
8 x=42
15
8 x÷
15
8 =42÷
15
8
x=22.4;
(2)(
5
8 +
5
6 )x=
7
10
35
24 x=
7
10 ,
35
24 x÷
35
24 =
7
10 ÷
35
24 ,
x=
12
25 ;
(3)
4
5 ×5-12x=1
4-12x=1,
4-12x+12x=1+12x,
1+12x=4,
1+12x-1=4-1,
12x=3,
12x÷12=3÷12,
x=
1
4 .