(1)
1
2 +
5
7 ×
7
10 ,
=
1
2 +
1
2 ,
=1;
(2)
1
2 +
8
3 ÷
2
9 ,
=
1
2 +
8
3 ×
9
2 ,
=
1
2 +12,
=12
1
2 ;
(3)18×(3-
2
9 ),
=18×3-18×
2
9 ,
=54-4,
=50;
(4)12×
3
4 +12×
1
4 ,
=12×(
3
4 +
1
4 ),
=12×1,
=12;
(5)
1
7 +
3
8 +
6
7 +
5
8 ,
=(
1
7 +
6
7 )+(
3
8 +
5
8 ),
=1+1,
=2;
(6)
5
4 ×
1
9 +
3
4 ÷9,
=
5
4 ×
1
9 +
3
4 ×
1
9 ,
=(
5
4 +
3
4 )×
1
9 ,
=2×
1
9 ,
=
2
9 .