(1)
7
13 ×
1
5 ×39,
=(
7
13 ×39)×
1
5 ,
=21×
1
5 ,
=
21
5 ;
(2)45×
1
7 +
6
7 ×45,
=45×(
1
7 +
6
7 ),
=45×1,
=45;
(3)(
2
3 -
1
2 +
1
6 )÷
1
24 ,
=(
2
3 -
1
2 +
1
6 )×24,
=
2
3 ×24-
1
2 ×24+
1
6 ×24,
=16-12+4,
=8.
(1)
7
13 ×
1
5 ×39,
=(
7
13 ×39)×
1
5 ,
=21×
1
5 ,
=
21
5 ;
(2)45×
1
7 +
6
7 ×45,
=45×(
1
7 +
6
7 ),
=45×1,
=45;
(3)(
2
3 -
1
2 +
1
6 )÷
1
24 ,
=(
2
3 -
1
2 +
1
6 )×24,
=
2
3 ×24-
1
2 ×24+
1
6 ×24,
=16-12+4,
=8.