①
12
13 ×
3
7 +
4
7 ×
12
13 +
12
13 ,
=(
3
7 +
4
7 +1)×
12
13 ,
=2×
12
13 ,
=1
11
13 ;
②9.6-11÷7+
1
7 ×4, =9.6-(
11
7 -
4
7 ),
=9.6-1,
=8.6;
③34÷[8
1
3 -(6
3
5 +5
2
5 ÷9)],
=34÷[8
1
3 -(6
3
5 +
27
5 ×
1
9 )],
=34÷[8
1
3 -(6
3
5 +
3
5 )],
=34÷[8
1
3 -7
1
5 ],
=34÷
17
15 ,
=30;
④[9-(
1
12 +
1
8 )×24]÷1
3
5 ,
=[9-(
1
12 +
1
8 )×24]÷1
3
5 ,
=[9-(24×
1
12 + 24×
1
8 )]÷1
3
5 ,
=[9-(2+3)]÷1
3
5 ,
=[9-5]÷1
3
5 . =4×
5
8 ,
=2
1
2 ;