bonjour,
3 x - 7 = 44
3 x = 44 + 7
3 x = 51
x = 17
4 x + 1 = - 2 x + 7
4 x + 2 x = 7 - 1
6 x = 6
x = 1
4 x + 8 = 5 x - 5
4 x - 5 x = - 5 - 8
- x = - 13
x = 13
2 x + 12 = 38
2 x = 38 - 12
2 x = 26
x = 13
côté = 13 cm
60 + 12 x < 16 x
12 x - 16 x < - 60
- 4 x < - 60
x > 15
le tarif abonné est plus rentable au delà de 15 séances