Seek wealth by referring to the answer.
One,
1
.
D
2
.
A
three
.
A
Second,
1
.
x
= - 6
2
.
2
x
-
15=25
three
.
x
=
three
( 12
-
x
)
Third,
1
.
Solution: Set up water for production and operation.
x
Billion cubic meters
,
Household water consumption (
5.8
-
x
) 1 100 million cubic meters, and the equation can be listed as follows
：
5.8
-
x
=3
x+
0.6
2
.
Solution: Suppose an apple is bought.
x
kilogram
,
Then the countable equation is
：
four
x
+
three
(
five
-
x
)=
17
three
.
Solution: Let the number of students in the original extracurricular mathematics group be
x
The equation can be listed as follows
：
)
four
(
2
1
four
three
1
x
x
six
.
2
Solve a linear equation with one variable
(
one
)