\(\left(-\dfrac{3}{5}\right)^{15}:\left(-\dfrac{9}{25}\right)^7=\left(-\dfrac{3}{5}\right)^{15}:\left(-\dfrac{3}{5}\right)^{14}=-\dfrac{3}{5}\)
\(\left(-\dfrac{3}{5}\right)^{15}:\left(-\dfrac{9}{25}\right)^7=\left(-\dfrac{3}{5}\right)^{15}:\left(-\dfrac{3}{5}\right)^{14}=\left(-\dfrac{3}{5}\right)\)