Équations a résoudre

1.  4x - 7 = 11x + 33 => 4x - 11x = 33+7 => -7x = 40 => x = -40/7
2 .5x + 21 - 6x = 6x + 1 => -7x = -20 => x = 20/7
3. 5x + 10 + 4x = 30 - 3x => 12x = 20 => x = 20/12 = 5/3
4.18x = -1 => x = -1/18