Ответ:

a) x - 8/15x = 7/15

7/15x = 7/15

x = 1

б) x -7/9x = 1 1/3

x - 7/9x = 4/3

2/9x = 4/3

x = (4×9)/(3×2)

x = 6

в) k - 1/6k = 5

5/6k = 5

k = (6×5)/5

k = 6

г) (7,1c + c) : 0,3 = 189

7,1c + c = 56,7

8,1c = 56,7

c = 7