Answer
$$-\frac{3}{4x}$$
Work Step by Step
Multiplying the $2x-5$ to the numerator, we find:
$$\frac{\left(\frac{1}{2x-5}-\frac{7}{8x-20}\right)\left(2x-5\right)}{x} \\ \frac{\left(-\frac{3}{4\left(2x-5\right)}\right)\left(2x-5\right)}{x} \\ -\frac{\frac{3}{4}}{x}\\ -\frac{3}{4x}$$