(1)[1-(
1
4 +
3
8 )]÷
1
24 ,
=[1-
5
8 ]÷
1
24 ,
=
3
8 ÷
1
24 ,
=9;
(2)
1
7 ×
2
3 ÷(
4
5 -
8
15 ),
=
1
7 ×
2
3 ÷
4
15 ,
=
2
21 ÷
4
15 ,
=
5
14 ;
(3)75-7.5+25-42
1
2 ,
=(75+25)-(7.5+42
1
2 ),
=100-50,
=50;
(4)
1
7 +
7
8 ×
5
7 +
3
8 ,
=
1
7 +
5
8 +
3
8 ,
=
1
7 +(
5
8 +
3
8 ),
═
1
7 +1,
=1
1
7 ;
(5)0.8×4×12.5×2.5,
=(0.8×12.5)×(2.5×4),
=10×10,
=100;
(6)65-40÷1
2
3 ×12.5%,
=65-24×12.5%,
=65-3,
=62.