Besoin d'aide sur les équations je comprend rien:

bonjour

x + 7 = 2 x + 4

x - 2 x = 4 - 7

- x = - 3

x = 3

x - 1 = - 8 x + 1

x + 8 x = 1 + 1

9 x = 2

x = 2/9

2 x + 4 = 4 x - 5

2 x - 4 x = - 5 - 4

- 2 x = - 9

x = 9 /2

3 x - 9 = 2 + 9 x

3 x - 9 x = 2 + 9

- 6 x =  11

x = - 11 /6

continue

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4 x - 7 = 53

4 x = 53 + 7

4 x = 60

x = 15

3 ( x + 10 ) = 5 x

3 x + 30 = 5 x

3 x - 5 x = - 30

- 2 x = - 30

x = 15

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12 x =  1020

x = 85

85 livres vendus

99 + 2 x = 127

2 x = 127 - 99

2 x = 28

x = 14

T shirt  = 14 €

5 x = 3 x + 18

5 x - 3 x = 18

2 x = 18

x = 9

Bd = 9 €

x + 2 x = 24

3 x = 24

x = 8

8 + 16 = 24