\(=\dfrac{1.4.9.16}{2.6.12.20}=\dfrac{576}{2880}=\dfrac{1}{5}\)
\(\dfrac{1}{2}\cdot\dfrac{4}{6}\cdot\dfrac{9}{12}\cdot\dfrac{16}{20}=\dfrac{1}{2}\cdot\dfrac{2\cdot2}{2\cdot3}\cdot\dfrac{3\cdot3}{3\cdot4}\cdot\dfrac{4\cdot4}{4.5}=\dfrac{1}{5}\)
\(=\dfrac{1.4.9.16}{2.6.12.20}\)
\(=\dfrac{1.2.2.3.3.4.4}{2.2.3.3.4.4.5}\)
\(=\dfrac{1}{5}\)