Multiply whole equation by x-4 and then 2x+1 (would do this one step at a time but must conserve space here):
(2x+3)(2x+1)-(2x-8)(x-4)=(x-4)(2x+1)
Expand brackets:
(4x^2+8x+3)-(2x^2-16x+32)= 2x^2-7x-4
Do the subtraction: 2x^2+24x-29=2x^2-7x-4
Minus 2x^2 from both sides:
24x-29=-7x-4
Bring Xs to left hand side and integers to right hand side of equals sign:
31x=25
X=25/31