How do you simplify (-9f^3g^5h^2)/(6fg^2h )?

This expression can be simplified using properties of exponents. That is, if both the denominator and the numerator are one term, or if there is a common variable between both the numerator and denominator (e.g $\frac{{f}^{2} \left(5 h + 4 k\right)}{f \left(2 k + 5 h\right)}$, the shared variable on both sides of the division bar can be cancelled out.
In the example earlier, the ${f}^{2}$ in the numerator will become $f$ and the denominator's $f$ will cancel out: $\frac{f \left(5 h + 4 k\right)}{\left(2 k + 5 h\right)}$
$\frac{- 3 {f}^{2} {g}^{3} h}{2}$