计算 21÷(1/3+2/5)÷9/11 2.23×2/5+2.77÷2.5  7/8÷[1/3×(3/2-3/4)].

问题描述:

计算
21÷(

1
3
+
2
5
)÷
9
11

2.23×
2
5
+2.77÷2.5   
7
8
÷[
1
3
×(
3
2
-
3
4
)].

(1)21÷(

1
3
+
2
5
)÷
9
11

=21÷
11
15
÷
9
11

=
315
11
÷
9
11

=35;
(2)2.23×
2
5
+2.77÷2.5,
=0.892+1.108,
=2;
(3)
7
8
÷[
1
3
×(
3
2
-
3
4
)],
=
7
8
÷[
1
3
×
3
4
],
=
7
8
÷
1
4

=3
1
2