(1)
4
5 ×
3
8 +
4
5 ×
1
2
=
4
5 ×(
3
8 +
1
2 )
=
4
5 ×
7
8
=
7
10 ;
(2)(3×
5
12 )×4
3
7 ×
2
9 ×
7
8
=3×
5
12 ×
31
7 ×
2
9 ×
7
8
=
155
144 ;
(3)
4
9 ×
2
3 +
2
3 ×
5
9
=(
4
9 +
5
9 )×
2
3
=1×
2
3
=
2
3 ;
(4)14×
7
13 -
7
13
=(14-1)×
7
13
=13×
7
13
=7;
(5)(
1
3 +
1
4 )×12
=
1
3 ×12+
1
4 ×12
=4+3
=7.