Under the absolute value could be positive or negative number, but absolute value make them both positive. For positive number we can write is (4x+3) and for negative -(4x+3) 4x+3<9 4x< 6 x< 3/2 (-∞, 3/2)
-(4x+3)<9 -4x-12<9 -4x<21 x>-21/4 (-21/4, +∞)
(-∞, 3/2)∩ (-21/4, +∞) =(-21/4, 3/2) it could be written as (-5.25, 1.5)
