(1)13
4
19 +86
15
19 ×0.25+0.625×86
15
19 +86
15
19 ×
1
8 ,
=13
4
19 +86
15
19 ×(
1
4 +
5
8 +
1
8 ),
=13
4
19 +86
15
19 ×1,
=100;
(2)(
1
2 +1
1
12 )÷2
1
9 ÷(2-0.25),
=(
6
12 +1
1
12 )×
1
19 ÷
7
4 ,
=
19
12 ×
1
19 ×
4
7 ,
=
1
12 ×
4
7 ,
=
1
21 ;
(3)2-
6
13 ÷
9
26 -
2
3 +
8
15 ÷0.6×
2
3 ,
=2-
6
13 ×
26
9 -
2
3 +
8
15 ÷
3
5 ×
2
3 ,
=2-
4
3 -
2
3 +
8
15 ×
5
3 ×
2
3 ,
=2-(
4
3 +
2
3 )+
16
27
=0 +
16
27 ,
=
16
27 ;
(4)2008×1
1
2 ÷1
1
3 -100
2
5 ÷
1
20 ,
=2008×
3
2 ×
3
4 -
502
5 × 20,
=502×
9
2 -502×4,
=502×(
9
2 -
8
2 ),
=502×
1
2 ,
=251.