Question

求未知数x①310x-21×23=4　 &nbs...

求未知数x①310x-21×23=4　 ②115x+25x=415 ③0.25x=1.253 ④x×（34-23）=23．

Answer 1

①

3

10

x-21×

2

3

=4
        

3

10

x-14=4　
     

3

10

x-14+14=4+14
       

3

10

x÷

3

10

=18÷

3

10

              x=60．

②1

1

5

x+

2

5

x=

4

15

      

8

5

x=

4

15

   

8

5

x÷

8

5

=

4

15

÷

8

5

        x=

1

6

．

③

0.25

x

=

1.25

3

      1.25x=0.25×3
1.25x÷1.25=0.75÷1.25
          x=0.6．

④x×（

3

4

-

2

3

）=

2

3

       x×

1

12

=

2

3

    x×

1

12

÷

1

12

=

2

3

÷

1

12

            x=8．