(1)8-
3
19 ×5-
4
19 ,
=8-
15
19 -
4
19 ,
=8-(
15
19 +
4
19 ),
=8-1,
=7;
(2)
5
9 ×(
3
5 +
9
10 ),
=
5
9 ×
3
5 +
5
9 ×
9
10 ,
=
1
3 +
1
2 ,
=
5
6 .
(1)8-
3
19 ×5-
4
19 ,
=8-
15
19 -
4
19 ,
=8-(
15
19 +
4
19 ),
=8-1,
=7;
(2)
5
9 ×(
3
5 +
9
10 ),
=
5
9 ×
3
5 +
5
9 ×
9
10 ,
=
1
3 +
1
2 ,
=
5
6 .