k) \(\left(\frac{1}{9}\right)^{25}:\left(\frac{1}{3}\right)^{30}\)
\(=\left[\left(\frac{1}{3}\right)^2\right]^{25}:\left(\frac{1}{3}\right)^{30}\)
\(=\left(\frac{1}{3}\right)^{50}:\left(\frac{1}{3}\right)^{30}\)
\(=\left(\frac{1}{3}\right)^{50-30}\)
\(=\left(\frac{1}{3}\right)^{20}\)
h) \(\left(\frac{1}{2}\right)^{15}.\left(\frac{1}{4}\right)^{20}\)
\(=\left(\frac{1}{2}\right)^{15}.\left[\left(\frac{1}{2}\right)^2\right]^{20}\)
\(=\left(\frac{1}{2}\right)^{15}.\left(\frac{1}{2}\right)^{40}\)
\(=\left(\frac{1}{2}\right)^{15+40}\)
\(=\left(\frac{1}{2}\right)^{55}\)