помогите пожалуйста ​

Ответ:

Пошаговое объяснение:

1)

(12 + x) : (-3) = (-7) : 3,5

(12 + x) : (-3) = -2

12 + x = -2 * (-3)

12 + x = 6

x = 6 - 12

x = -6

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2)

(x - 9) : (-1,8) = (-2,5) : (-0,5)

(x - 9) : (-1,8) = 5

x - 9 = 5 * (-1,8)

x - 9 = -9

x = -9 + 9

x = 0

-------------------------

3)

4 * (x - 2) = 3 *(-7 - x)

4x - 8 = -21 - 3x

4x + 3x = -21 + 8

7x = -13

x = -13 : 7

x = -1 6/7

------------------------

4)

8 * (4 + x) = 20 * (3 - x)

32 + 8x = 60 - 20x

8x + 20x = 60 - 32

28x = 28

x = 1