1) 3/x+1=2/3
2) 5/1/4:2/1/3=1/1/5x:1/1/3
3) 25:x=5:4

Пошаговое объяснение:

1)

3/(х + 1) = 2/3

2 * (х + 1) = 3 * 3

2х + 2 = 9

2х = 9 - 2

2х = 7

х = 7 : 2

х = 3,5

2)

5. 1/4 : 2. 1/3 = (1. 1/5)х : 1. 1/3

21/4 : 7/3 = (6/5)х : 4/3

(6/5)х * 7/3 = 4/3 * 21/4

(42/15)х = 84/12

(14/5)х = 7

х = 7 : 14/5

х = 7 * 5/14

х = 1 * 5/2

х = 5/2

х = 2. 1/2

3)

25 : х = 5 : 4

5 * х = 4 * 25

5х = 100

х = 100 : 5

х = 20