问题 解答题
正确、合理、灵活的计算,求未知数
1.25×4×0.6×0.8×2.5
5
16
×[2
2
5
+(
2
3
-
2
5
)÷
1
3
]
4
1
5
+4.2×7
5
7
+1
2
7
×4
1
5
3
1
2
×1
1
5
÷(4.5-0.625÷
5
16
)÷30%
1
1
5
:1
2
7
=X:
9
14
5×0.36-0.75X=
3
5
答案

(1)1.25×4×0.6×0.8×2.5,

=(1.25×0.8)×(2.5×4)×0.6,

=1×10×0.6,

=6;

(2)

5
16
×[2
2
5
+(
2
3
-
2
5
)÷
1
3
],

=

5
16
×[2
2
5
+(
2
3
-
2
5
)÷
1
3
],

=

5
16
×[2
2
5
+(
10
15
-
6
15
)×3],

=

5
16
×[2
2
5
+
4
15
×3
],

=

5
16
×[2
2
5
+
4
5
],

=

5
16
×
16
5

=1;

(3)4

1
5
+4.2×7
5
7
+1
2
7
×4
1
5

=4.2+4.2×7

5
7
+1
2
7
×4.2,

=4.2×(1+7

5
7
+1
2
7
),

=4.2×10,

=42;

(4)3

1
2
×1
1
5
÷
(4.5-0.625÷
5
16
)÷30%,

=

7
2
×
6
5
÷(4.5-
5
8
×
16
5
)×
10
3

=

21
5
÷(4.5-2)×
10
3

=

21
5
×
2
5
×
10
3

=(

21
5
×
10
3
)×
2
5

=14×

2
5

=

28
5

=5

3
5

(5)1

1
5
:1
2
7
=X:
9
14

1

2
7
x=1
1
5
×
9
14

1

2
7
x=
6
5
×
9
14

9
7
7
9
=
6
5
×
9
14
×
7
9

x=

6
5
×(
9
14
×
7
9
),

x=

6
5
×
1
2

x=

3
5

(6)5×0.36-0.75X=

3
5

1.8-0.75x=0.6,

0.75x=1.2,

3
4
4
3
=1.2×
4
3

x=1.6;

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