Explanation:
a) x + 4 = 12
=> x + 4 - 4 = 12 - 4
=> x = 8
d) - 14 = 2x
=> -14/2 = 2x/2
=> -7 = x
x = -7
b) x + 5,1 = x + x
1 = x + x
1 = 2x
1/2 = 2x/2
x = 1/2 or 0.5
e) 5 = 4x
=> 5/4 = 4x/4
=> x = 5/4 or 0.8
c) 6x = x - 15
=> x - 15 = 6x
=> -15 = 6x - x
=> -15 = 5x
=> -15/5 = 5x/5
=> x = -3
f) x + 8 = 2x + 3
x+8=2x+3
x+8−2x=2x+3−2x
−x+8=3
−x+8−8=3−8
−x=−5
−x/−1 = −5/−1
x=5
J'espère que cela vous aidera, si vous avez d'autres problèmes, dites-le moi