①x-

3

4

x=

3

10

1

4

x=

3

10

1

4

x×4=

3

10

×4

x=1.2

②x÷

7

5

+

1

5

=

4

5

x×

5

7

+

1

5

=

4

5

x×

5

7

+

1

5

-

1

5

=

4

5

-

1

5

5

7

x×

7

5

=

3

5

×

7

5

x=

21

25

③

5

6

÷x=

1

3

5

6

×x÷x=

1

3

×x

1

3

x×3=

5

6

×3

x=2.5