(1)
6
7 ÷[(
4
7 -
1
2 )×
2
5 ]
=
6
7 ÷[
1
14 ×
2
5 ]
=
6
7 ÷
1
35
=
6
7 ×35
=30;
(2)
14
15 ×25%-
11
15 ÷4
=
14
15 ×
1
4 -
11
15 ×
1
4
=(
14
15 -
11
15 )×
1
4
=
1
5 ×
1
4
=
1
20 ;
(3)1.28×2.37-2.8×0.237
=1.28×2.37-0.28×2.37
=(1.28-0.28)×2.37
=1×2.37
=2.37;
(4)(
5
12 +
1
19 )×12+
7
19
=
5
12 ×12+
1
19 ×12+
7
19
=5+(
12
19 +
7
19 )
=5+1
=6.