\(=\left(-\dfrac{3}{5}\right)^{12}:\dfrac{\left(\dfrac{3}{10}\right)^{15}}{2^{10}}\)
\(=\left(-\dfrac{3}{5}\cdot2\right)^{10}\cdot\dfrac{9}{25}:\left(\dfrac{3}{10}\right)^{15}\)
\(=\left(-\dfrac{6}{5}\right)^{10}\cdot\dfrac{10^{15}}{3^{15}}\cdot\dfrac{9}{25}\)
\(=\dfrac{2^{10}\cdot3^{10}}{5^{10}}\cdot\dfrac{5^{15}\cdot2^{15}}{3^{13}}\cdot\dfrac{1}{5^2}\)
\(=\dfrac{2^{25}}{3^3}\cdot5^2\)