3x+1/14=3/7; 98/x-9=7; x+3/8=10; 2x-1/10=3/5.

1)

3 х + 1/14 = 3/7

3 х = 3/7 - 1/14

3 х = 6/14 - 1/14

3 х = 5/14

х = 5/14 : 3

х = 5/14 * 1/3

х = 5/42

проверка:

3 * 5/42 + 1/14 = 3/7

15/42 + 3/42 = 18/42

18/42 = 18/42

2)

98/х - 9 = 7

98 : х = 7 + 9

98 : х = 16

х = 98 : 16

х = 98/16

х = 6 2/16

х = 6 1/8

проверка:

98 : 6 1/8 - 9 = 7

98 : 49/8 - 9 = 7

98 * 8/49 - 9 = 7

2 * 8 - 9 = 7

16 - 9 = 7

7 = 7

3)

х + 3/8 = 10

х = 10 - 3/8

х = 9 8/8 - 3/8

х = 9 5/8

проверка:

9 5/8 + 3/8 = 10

9 8/8 = 10

10 = 10

4)

2 х - 1/10 = 3/5

2 х = 3/5 + 1/10

2 х = 6/10 + 1/10

2 х = 7/10

х = 7/10 : 2

х = 7/10 * 1/2

х = 7/20

проверка:

2 * 7/20 - 1/10 = 3/5

14/20 - 1/10 = 3/5

7/10 - 1/10 = 3/5

6/10 = 3/5

3/5 = 3/5