Answer
$\frac{9}{x^2}$
Work Step by Step
We can simplify by canceling out common factors of both fractions and then multiplying.
Multiplying 2 negatives yields a positive product.
$-\frac{24x}{5}\times-\frac{15}{8x^3}=-\frac{3\times/\!\!8\times /\!\!x}{/\!\!5}\times-\frac{3\times/\!\!5}{/\!\!8\times /\!\!x\times x^2}=\frac{3\times3}{x^2}=\frac{9}{x^2}$