合理、灵活地计算 ①4/5×3.5+5.5×80%+0.8        ②(7/17×19-7/17)×17/18 ③15/6÷[6/11×(5/9-1/4)] ④2.35÷[4.75-4.5×(0.2+1/3)].

问题描述:

合理、灵活地计算

4
5
×3.5+5.5×80%+0.8       
②(
7
17
×19-
7
17
)×
17
18

③1
5
6
÷[
6
11
×(
5
9
-
1
4
)]
④2.35÷[4.75-4.5×(0.2+
1
3
)].

4
5
×3.5+5.5×80%+0.8,
=0.8×3.5+5.5×0.8+0.8,
=(3.5+5.5+1)×0.8,
=10×0.8,
=8;
②(
7
17
×19-
7
17
)×
17
18

=[(19-1)×
7
17
17
18

=18×
7
17
×
17
18

=7;
③1
5
6
÷[
6
11
×(
5
9
-
1
4
)],
=
11
6
÷[
6
11
×
11
36
],
=
11
6
÷
1
6

=
11
6
×6,
=11;
④2.35÷[4.75-4.5×(0.2+
1
3
)],
=2.35÷[4.75-4.5×(
1
5
+
1
3
)],
=2.35÷[4.75-4.5×
8
15
],
=2.35÷[4.75-2.4],
=2.35÷2.35,
=1.