16) \( \frac{2 p r q^{-3} \cdot 2 q r p^{2}}{(2 p)^{3}} \)

To simplify the expression \( \frac{2 p r q^{-3} \cdot 2 q r p^{2}}{(2 p)^{3}} \), first, we can multiply the numerators: Numerator: \( 2 p r q^{-3} \cdot 2 q r p^{2} = 4 p^3 r^2 q^{-3} \). Now, simplify the denominator: Denominator: \( (2 p)^{3} = 8 p^{3} \). Now, plug these into the fraction: \[ \frac{4 p^3 r^2 q^{-3}}{8 p^{3}}. \] Next, we can simplify this by dividing the coefficients and cancelling out \( p^3 \): \[ \frac{4}{8} \cdot \frac{r^2}{1} \cdot \frac{1}{q^{3}} = \frac{1}{2} r^2 q^{-3}. \] So, the simplified result is: \[ \frac{r^2}{2 q^{3}}. \]