Bonjour :
A) 3x+1 > 0 => 3x > -1 => x > -1/3
B) 3x-(5x+7) ≥ 2x-3 => 3x-5x-7 ≥ 2x-3 => -2x -7 ≥ 2x-3 => 0 ≥ 2x+2x+7-3 =>
4x + 4 ≤ 0 => x ≤ -1
C) 2x-5 / 3 < 2x -3/7 => 2x/3 -5/3 < 2x -3/7 => 3/7 -5/3 < 2x - 2x/3
=> 9/21 - 35/21 < 4x/3 => -26/21 < 28x/21 => -26 < 28x => x > -26/28 =>
x> - 13/14