\(\frac{16.\left(-2x^2y\right)^2.\left(-axy\right)}{5b}\)
\(=\frac{-16\left(-2x^2y\right).axy}{5b}\)
\(=\frac{-16axy\left(-2x^2y\right)^2}{5b}\)
\(=\frac{-16axy\left(2x^2y\right)^2}{5b}\)
\(=-\frac{16\left(2x^2y\right)^2axy}{5b}\)
\(=-\frac{2^2.16ax^5y^3}{5b}\)
\(=-\frac{64ax^5y^3}{5b}\)