La reponse svp il me le faut vite svp

1. ax+b = d
2x + 3 = 7
2x = 7-3
x = 4/2
x = 2

cx+b=b
5x + 3 = 3
5x = 3-3
x = 0/5
x = 0
(pas sure pour celle ci)

ax -c=d
2x - 5 = 7
2x = 7-5
x = 2/2
x = 1

2. et le 2 je ne sais pas