Answer
$\dfrac{10-3x}{2x^2}$
Work Step by Step
RECALL:
$(f-g)(x) = f(x)-g(x)$
Using the formula above gives:
$(r-t)(x)
\\= r(x)-t(x)
\\=\dfrac{5}{x^2}-\dfrac{3}{2x}$
Make the expressions similar using their LCD $2x^2$
$=\dfrac{5(2)}{x^2(2)}-\dfrac{3(x)}{2x(x)}
\\=\dfrac{10}{2x^2}-\dfrac{3x}{2x^2}
\\=\dfrac{10-3x}{2x^2}$