① (
1
8 -
1
4 ÷4×
1
4 )÷
1
2 ,
=(
1
8 -
1
4 ×
1
4 ×
1
4 )×2,
=(
1
8 -
1
64 )×2,
=
7
64 ×2,
=
7
32 ;
②
2
3 x+
1
2 x-
2
3 =0.5 ,
7
6 x=
2
3 +
1
2 ,
7
6 x=
7
6 ,
x=1.
③ 8.6×8.6+8.6×
2
5 +8.6 ,
=(8.6+
2
5 +1)×8.6,
=10×8.6,
=86.
④ 1
1
3 -
7
12 +
9
20 -
11
30 +
13
42 -
15
56 ,
=1+
1
3 -
7
12 +
9
20 -
11
30 +
13
42 -
15
56 ,
=1+
1
3 -
3+4
3×4 +
4+5
4×5 -
5+6
5×6 +
6+7
6×7 -
7+8
7×8 ,
=1+
1
3 -
1
3 -
1
4 +
1
4 +
1
5 -
1
5 -
1
6 +
1
6 +
1
7 -
1
7 -
1
8 ,
=1-
1
8 ,
=
7
8 .