Bonjour je vous en supplie pouvez vous m'aidez pour ces 3 minis exercices ? merci beaucoup

Exercice 3 : 

a. 2x - 4 = 3 - 5x
2x + 5x = 3 + 4
7x = 7
x = 7/7
x = 1

b. x - 2 = 5x - 4
x - 5x = - 4 + 2
- 4x = - 2
x = - 2 / (- 4)
x = 0,5

Exercice 4 : 

a. x + 5 = - 4x + 3
x + 4x = 3 - 5
5x = - 2
x = - 2/5
x = - 0,4

b. 30 + 5t = 2 - 2t
5t + 2t = 2 - 30
7t = - 28
t = - 28/7
t = - 4

Exercice 5 :

a. 6 - x = 5 - 4x
- x + 4x = 5 - 6
3x = - 1
x = - 1/3

b. 8y - 7 = - 12y + 2
8y + 12y = 2 + 7
20y = 9
y = 9/20
y = 0,45