Ответ:

Пошаговое объяснение:

1) (2/3)/(4/9 ·x -4/9) +1/20=4/5

(2/3)/(4/9 ·(x-1))=16/20 -1/20

4/9 ·(x-1)=(2/3)/(3/4)

x-1=2/3 ·4/3 ·9/4

x-1=2

x=2+1=3

2) (5/7)/(6/7 ·x +3/7) -1/2=1/6

(5/7)/(3/7 ·(2x+1))=1/6 +3/6

3/7 ·(2x+1)=(5/7)/(2/3)

2x+1=5/7 ·3/2 ·7/3

2x+1=5/2

2x=5/2 -2/2

x=3/2 ·1/2=3/4=0,75

3) (3/4)/(5/8 ·x -1/2) -1/8=1/4

(3/4)/(1/2 ·(5/4 ·x-1))=2/8 +1/8

1/2 ·(5/4 ·x-1)=(3/4)/(3/8)

1/2 ·(5/4 ·x-1)=3/4 ·8/3

5/4 ·x-1=2·2

5/4 ·x=4+1

x=5·4/5=4