Équations niveau 4ème (exercice 2) svp merci

-9-8x =15
-8x = 15+9
-8x = 24
x=  -24/8
x = -3


x+7-3x = -21
x-3x= -21 -7
-2x =  -28
x = -28/ -2
x = 14

10x -3(2x -15) = -3
10x -6x+45 = -3
10x -6x = -3-45
4x = -48
x = -48/4
x = -12

a) -9-8x=15
-8x=15+9
x=24/(-8)
x=-3

b) x+7-3x=-21
x-3x=-21-7
-2x=-28
x=(-28)/(-2)
x=14

c) 10x -3(2x-15)=-3
10x-6x+45=-3
10x-6x=-3-45
4x=-48
x=(-48)/4
x=-12