Найдите неизвестный член пропорции​

Пошаговое объяснение:

x : 8 = 4 : 2

2*x = 8*4

2x = 32

x = 32 : 2

x = 16

7,8 : x = 7,2 : 1,2

7,2*x = 7,8*1,2

7,2x = 9,36

x = 9,36 : 7,2

x = 1,3

2 2/7 : 1 1/7 = x : 2 1/9

1 1/7 * x = 2 2/7 * 2 1/9

8/7x = 16/7 * 19/9

8/7x = 304/63

x = 304/63 * 7/8

x = 38/9

x = 4 2/9

5 : 4 = 2,5 : x

5*x = 2,5*4

5x = 10

x = 10 : 5

x = 2

1) x/8 = 4/2

x = 8 × 4/2

x = 16

2) 7,8/x = 7,2/1,2

x = 7,8 × 1,2/7,2

x = 1,3

3) 2 2/7 / 1 1/7 = x/ 2 1/9

x = 2 2/7 × 2 1/9 / 1 1/7

x = 32/63 × 7/8

x = 4/9

4) 5/4 = 2,5/x

x = 4 × 2,5/5

x = 2