Réponse :
Explications étape par étape
Bsr,
(x+60)/2 = 50
x+60 = 50*2 = 100
x=100-60 = 40
x=40
2)
2x- 9 = -8 +x
2x-x = -8+9 = 1
x=1
3°
3x +15 = 2(x+8)
3x+15 = 2x+16
3x-2x = 16 -15
x= 1
4°
(5x/7) +12 = (4x/7) -8
(5x/7) - (4x/7) = -8 -12
x/7 = -20
x= -20*7 = -140
x= -140
☺