№20. \(\dfrac{10^9}{(2^5)^2\cdot5^7}\)

\(10^9=2^9\cdot5^9\), а \((2^5)^2=2^{10}\).

\(\dfrac{2^9\cdot5^9}{2^{10}\cdot5^7}=\dfrac{5^2}{2}=\dfrac{25}{2}\).

Ответ: \(\dfrac{25}{2}\).