(1)
5
9 ×(
9
5 +18),
=
5
9 ×
9
5 +
5
9 ×18,
=1+10,
=11;
(2)4÷
4
5 -
4
5 ÷4,
=5-
1
5 ,
=4
4
5 ;
(3)
1
2 ×
3
5 +
2
5 ×
1
2 ,
=
1
2 ×(
3
5 +
2
5 ),
=
1
2 ×1,
=
1
2 ;
(4)
1
7 ×
5
13 +
8
13 ÷7,
=
1
7 ×
5
13 +
8
13 ×
1
7 ,
=
1
7 ×(
5
13 +
8
13 ),
=
1
7 ×1,
=
1
7 ;
(5)19-19×
99
100 ,
=19×(1-
99
100 ),
=19×
1
100 ,
=
19
100 ;
(6)
7
8 -
4
9 ×
3
8 ,
=
7
8 -
4
24 ,
=
17
24 .