①2.4×58+84×1.2
=2.4×58+42×2.4,
=2.4×(58+42),
=2.4×100,
=240;
②38×
36
37
=(37+1)×
36
37 ,
=37×
36
37 +1×
36
37 ,
=36+
36
37 ,
=36
36
37 ;
③
4
29 ×[1-(
3
4 -
3
8 )]
=
4
29 ×(1-
3
8 ),
=
4
29 ×
5
8 ,
=
5
58 ;
④112÷55
55
64
=112÷
55×64+55
64 ,
=112÷
55×(64+1)
64 ,
=112÷
55×65
64 ,
=112×
64
55×65 ,
=
7168
3575 .
⑤
8
17 ÷23+
1
23 ×
9
17
=
8
17 ×
1
23 +
1
23 ×
9
17 ,
=
1
23 ×(
8
17 +
9
17 ),
=
1
23 ×1,
=
1
23 .