de l'aide svp je n'y arrive pas

a/  2x -5
2(1/3) -5
2/3-5
2/3-15/3
-13/3

b/

2x-5 = -4
2x = -4+5
2x = 1
x = 1/2

c /
2x-5 = 5/3
2x = 5/3+5
2x = 5/3+15/3
2x = 20/3
x = 20/3 *1/2
x = 20/6
x = 10/3