Multiply out the denominator, take care to multiply both sides of the equation:
(2x+3)(2x+1) - (2x-8)(x-4) = (2x+1)(x-4)
Expand the brackets, pay attention the the signs when multiplying, expecially the negative between the two sets of brackets on the left hand side.
4x2+2x+6x+3 - (2x2-8x-8x+32)=2x2-7x-4
4x2+2x+6x+3-2x2+8x+8x-32=2x2-7x-4
Group like terms on each side of the equation.
2x2+24x-29=2x2-7x-4
Bring all the terms to one side to leave a quadratic equation equal to 0. Remember to change the sign as you bring a term from one side to the other.
31x-25 = 0
Rearrange for x
x= 25/31 (=0.81)